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2013
AM Envelope
The potential of Additive Manufacturing for façade construction
Holger Strauß
AM Envelope
The potential of Additive Manufacturing for façade construction
Holger Strauß
Delft University of Technology, Faculty of Architecture,
Architectural Engineering + Technology department
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AM Envelope
The potential of Additive Manufacturing for façade construction
Proefschrift
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof. ir. K.C.A.M. Luyben,
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op maandag 14 januari 2013 om 12:30 uur
door HOLGER STRAUSS
Diplomingenieur für Architektur (FH), Hochschule Ostwestfalen-Lippe, Detmold
geboren te Wuppertal, Duitsland
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Dit proefschrift is goedgekeurd door de promotoren:
Prof. Dr.-Ing. U. Knaack
Prof. Dr.-Ing. H. Techen
Samenstelling promotiecommissie:
Rector Magnificus, Voorzitter
Prof. Dr.-Ing. U. Knaack, Technische Universiteit Delft, promotor
Prof. Dr.-Ing. H. Techen, Fachhochschule Frankfurt, promotor
Prof. Dr.-Ing. U. Pottgiesser, Hochschule Ostwestfalen-Lippe, Detmold
Prof. dr.-ir. A.C.J.M. Eekhout, Technische Universiteit Delft
Prof. dr.ir. N. Hopkinson, University of Sheffield
Prof. dr.ir. J.C. Paul, Technische Universiteit Delft
Prof. ir. R. Nijse, Technische Universiteit Delft, Reservelid
abe.tudelft.nl
Design: Sirene Ontwerpers, Rotterdam
ISBN 978-1481214339
ISSN 2212-3202
© 2013 Holger Strauß
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Contents (concise)
Abstract 7
1 Introduction 17
2 AM technologies for façade construction 29
3 Toward AM Envelopes 95
4 Use and application of AM in façade technology 137
5 Conclusion 179
6 Summary 193
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Contents (concise)
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Abstract
The continuous development of the building envelope over the past hundred years can
be exemplified by a few ground-breaking inventions. Firstly, the separation of primary
and secondary structure during the beginning of the 20th century; by implementing
a curtain wall façade to physically separate the façade from the building. This was
followed by the development of double façades and a growing technologisation and
use of the building envelope for building services and climate devices. Hereby the
development of the ‘Polyvalent Wall’ by Mike Davies at the beginning of the 1980ies
was a notable vision that formulated part of the building envelope as an active skin.
The realisation of such a concept of a compact building envelope that encompasses all
necessary supply units and building services in a very slender and integrated way has
still not been accomplished.
This vision has been followed by many technical developments; the latest being based
on decentralised building services that are inseparably connected to the façade. But
in spite of all these efforts, even forty years after Mike Davies‘ vision we are far from
their realisation. Therefore, realising a ‘dynamic building envelope’ is a goal yet to be
achieved.
One technology to materialise this desire is Additive Manufacturing (AM): Layered
production of parts from a 3D file. Over the past twenty years this technology has
evolved from a support tool for product development into an independent production
method.
The term ‘AM Envelope’ (Additive Manufacturing Envelope) describes the transfer of
this technology to the building envelope. Additive Fabrication is a building block that
aids in developing the building envelope from a mere space enclosure to a dynamic
building envelope. AM Envelope is an approach to this evolutionary step with the AM
technology. This is exemplarily concretised and illustrated with building components
for a post-beam façade, and then transferred to façade development over the next
thirty years.
This dissertation shows the potential of the additive methods for the development of
façade construction: Additive methods change the way we design, build and produce
building envelopes.
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Contents (extensive)
PART 1 AM Envelope
1 Introduction 17
1.1 Background 17
1.1.1 The façade 17
1.1.2 Additive Fabrication 18
1.2 Motivation 21
1.2.1 Engineering 21
1.2.2 Background AM 23
1.3 Hypothesis and sub-questions 24
1.4 Approach and methodology 25
2 AM technologies for façade construction 29
2.1 State of the art 30
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
The principle of additive processes 31
Materializing a 3D modell 32
Surface quality 32
Rapid Manufacturing 33
Rapid Tooling 34
2.2 Overview of the most common AM processes 35
2.2.1 AM for plastics 38
2.2.1.1
Stereolithography 38
2.2.1.2
Laser Sintering 40
2.2.1.3
Fused Deposition Modelling 41
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Contents (extensive)
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2.2.1.4
3D-Printing 42
2.2.1.5
PolyJet 44
2.2.2 Consumer applications 45
2.2.3 AM for metals 46
2.2.3.1
Laser Engineered Net Shaping 49
2.2.3.2
Direct Metal Deposition 50
2.2.3.3
Electron Beam Free Form Fabrication 50
2.2.3.4
Construction Laser Additive Directe 51
2.2.3.5
Selective Laser Melting 52
2.2.3.6
LaserCusing 53
2.2.3.7
Electronic Beam Melting 54
2.2.3.8
Direct Metal Laser Sintering 55
2.2.4 AM for large scale structures 55
2.2.4.1
Contour Crafting 55
2.2.4.2
D-Shape 57
2.3 Summary AM technologies 58
2.4 AM materials 65
2.4.1 Plastics 66
2.4.2 Metals 69
2.4.3 Other materials 71
2.5 AM evolution from new impulses 72
2.5.1 AM system technology 73
2.5.1.1
Size of the building chamber 73
2.5.1.2
Process speed 75
2.5.2 AM materials 77
2.5.2.1
Functionally Graded Materials 77
2.5.2.2
Digital materials 79
2.5.2.3
Programmed lightweight building structures 80
2.5.2.4
Smart Materials 81
2.5.2.5
Transferring AM materials to building technology 83
2.5.3 Automated building construction 85
2.5.3.1
Building construction robots 85
2.5.3.2
Digital Fabrication 87
2.6 Summary chapter two 89
2.6.1 AM Envelope? 89
2.6.2 Changing the production methods 89
2.6.3 Challenges 92
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AM Envelope
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3 Toward AM Envelopes 95
3.1 Building envelope requirements 95
3.2 Research approaches 100
3.3 Influence of AM on the development of façade constructions 102
3.3.1 Corner cleats 102
3.3.1.1
271.xx 104
3.3.1.2
272.xx 105
3.3.1.3
210.xx 107
3.3.2 T-Connector 108
3.3.3 Nodal point 114
3.3.3.1
Nematox I 114
3.3.3.2
Nematox II 116
3.4 Results from part optimization 122
3.4.1 Potential for façade application 123
3.5 Requirements for optimizing standard parts with AM 124
3.6 The need for an AM guideline 126
3.6.1 System check 126
3.6.2 Production check 128
3.6.3 Design rules 130
3.6.3.1
Optimization aspects 130
3.7 Summary chapter three 132
4 Use and application of AM in façade technology 137
4.1 Technological developments in the (near) future 137
4.2 Principles for AM Envelopes 141
4.2.1 Façade application 142
4.2.2 Direct Glass Fabrication 150
4.2.3 Customization 155
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4.2.4 Summarising assessment of the shown principles 159
4.2.4.1
Façade technology 159
4.2.4.2
Climate and comfort 159
4.2.4.3
Glass as a basic material for AM 161
4.2.4.4
Individualisation 161
4.3 Influence of AM on architecture 162
4.3.1 From design to built environment 162
4.3.2 Toward built representations 164
4.3.2.1
Mendelsohn, Einsteinturm 165
4.3.2.2
Cook & Fournier, Kunsthaus Graz 166
4.3.2.3
Gehry, Walt Disney Concert Hall 167
4.3.3 Potential for improvement using new technologies 168
4.3.4 Mass Customization 169
4.4 Economic efficiency of AM 172
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
Break-even point 173
Possible savings related to material consumption and weight 174
Batch size one 174
Development cost for introduction to the market 175
New markets 175
4.5 Summary chapter four 176
5 Conclusion 179
5.1 Answers to the sub-questions 180
5.2 Open questions 183
5.3 Explicit benefits for the façade 185
5.3.1 Nematox II – a realistic approach to system façades? 186
5.3.2 AM Envelope as a tangible goal 187
5.4 The potential of AM for façade construction 188
5.4.1
5.4.2
5.4.3
5.4.4
5.4.5
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Feasibility 188
Improvement of building construction 189
Requirements for the future handling of AM 189
Quality standards 190
Advancements 191
AM Envelope
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6 Summary 193
6.1 Summary 193
6.2 Samenvatting 195
6.3 Zusammenfassung 197
PART 2 Appendices
A I Additional information AM 203
AM history 203
AM technologies in detail 205
Fabbing 222
Software 227
Additional information on the research results 229
Spread the idea - ideation with AM 241
Standardization 245
Inspiration from bio-mimicry 246
New markets from AM 247
A II Additional information PhD thesis 257
Literature 257
References 258
Weblinks 264
Glossary 266
Index of figures and tables 268
A III Personal information 275
Curriculum Vitae 275
Acknowledgments 276
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Contents (extensive)
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Part 1
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AM Envelope
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1 Introduction
This dissertation is motivated by the opportunities that Additive Manufacturing (AM)
offers for producing components, structural designs and buildings. New technologies
appear regularly - finding the one capable of having a big impact is difficult. In the
case of the additive methods, the changes in our way of constructing and thinking of
complex mechanisms or geometries are predictable. Therefore an early examination of
the new methods is crucial to stay ahead or at least amongst the early adopters.
§ 1.1 Background
§ 1.1.1 The façade
To research the application potential of AM for the façade, we need to look at the
developments in façade technology. In simple terms, the technological development
of the building envelope as it applies to the buildings today can be narrowed down
to the past hundred years. The introduction of the curtain wall and its subsequent
development into the double façade is important because they are the basis of today’s
most commonly used façade types.[1]
However, in spite of these highly technological and very sophisticated façade systems,
the demand for a true building skin has not yet been fulfilled. Mike Davies expressed
this vision as early as in the Nineteen Eighties – and it still has not been reached. He
envisioned a façade panel with an array of different functional layers. One for example
would deal with sun shading, one would provide thermal insulation. All needed
functions would perform automatically according to the given conditions, powered
by self-generated energy from another layer within the wall. What was conceived as
a slender, multi-layered and multifunctional envelope is still being realised as 15 to
30 centimetre thick walls with a myriad of individual components – far from Davies’
vision. Even if the solutions sometimes are more adaptive than at the beginning of the
technical sophistication, such as the development form centralised to decentralised
building services, and the resulting immediate influence the user has on the indoor
climate.[2]
17Introduction
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Figure 1
Concept sketch of the Polyvalent Wall by Mike Davies.
In this thesis the Polyvalent Wall is used as an envision of how future building
envelopes should perform and how slender – aiming toward the human skin – they
could be elaborated. It is therefore used as a symbolic ambition and a starting point
to rethink our current façade technology and to stimulate technological development.
Davies’ idea is not meant as a realistic product example, but as one possible way to go.
§ 1.1.2 Additive Fabrication
‘Additive Fabrication’ summarises the family of additive methods as they are
understood today – in the year 2012. This includes ‘Rapid Prototyping (RP)’ with its
original intent to quickly generate illustrative models for product development. These
models are used as a physical basis for discussion immediately following the design
phase. But Additive Fabrication as a superordinate term also includes those fields of the
same family for which specific areas of application have evolved from the basic concept:
§ 2.1.5 Rapid Tooling (RM), which, in industrial mass production has changed the
manner of how production tools are made, as well as § 2.1.4 Rapid Manufacturing
(RM) which is specifically designed for the production of end use products that are
immediately usable without the need for subsequent production steps.
During the course of the development of the various methods and applications,
a multitude of terms was used for the vast field of Additive Fabrication: Rapid
Prototyping, Layered Fabrication, Rapid Manufacturing, Freeform Fabrication,
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AM Envelope
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Additive Fabrication, Layered Manufacturing, Direct Digital Manufacturing, Additive
Manufacturing, etc. The term ‘Additive Manufacturing (AM)’1 has evolved as a general
term for these technologies [3]; thus, in this text Additive Manufacturing (AM) is used
as a synonym for additive methods.
Figure 2
Overview ‘Additive Fabrication’; use and allocation of various terms for the different areas of the AM industry
Additive methods are characterised by adding layers of material to produce parts
without the need of tools or preforms („tool less“ [4]). For all the different types of
additive processes, 3D computer data is the basis for the manufacturing process. The
parts are developed on the computer. For manufacturing, the data is then translated
into a special computer language and generated with AM systems.
1
ASTM International Committee F42 on Additive Manufacturing Technologies: “AM: ~ process of joining
materials to make objects from 3D model data. Additive Manufacturing (AM) as opposed to subtractive
manufacturing methodologies. Usually with AM parts which are processed layer upon layer. Synonyms: additive
fabrication, additive processes, additive techniques, additive layer manufacturing, layer manufacturing, and
freeform fabrication.”
Reference [3]: ASTM, Typologies for layered fabrication processes, in ASTM F2792, A. USA, Editor. 2009, ASTM
International Committee F42 on Additive Manufacturing Technologies: Annual Book of ASTM Standards,
Volume 10.04
19Introduction
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As a new part of the production chain, additive fabrication will change the way
we design and produce as well as how we handle consumer goods and our built
environment. In order to make these changes tangible for façade construction, case
studies with realistic application concepts from the façade technology were conducted
for this research. Initially it was difficult to identify such applications for Additive
Manufacturing (AM) due to our habit to think subtractive rather than purely functional.
However, it did lead to an intensive examination of the technologies and to approaches
and results. Only a few initial steps into developing products with AM generate
many new approaches for façade construction. Relevant aspects include material
consumption, assembly as well as component performance in the façade system,
amongst others.
Examining these approaches provides an indication of the manner and depth of the
possible changes in the design process of façade constructions as well as possible
changes in building construction and architecture in general. Examining these changes
allows us to identify the potential of Additive Manufacturing.
The development of AM is still in the beginning stage; however, AM technologies
offer the potential to lastingly change design and construction methods. The change
in our way of thinking has long begun: file-to-factory, Building Integrated Modelling
(BIM), digital materials are the key words in this ongoing discussion in the day and
age of Grashopper2. Ideas that have been put on paper can no longer be stopped; their
realisation is only a question of time. With the AM technologies the ‘façade’ as a mere
enclosure could evolve into a ‘dynamic building envelope’ – analogous to the human
being: a true skin. Further development of the new technologies is progressing rapidly;
it is foreseeable that AM will be intuitively and naturally used in the future and, thus,
find an application in many new areas – even in the somewhat conservative building
sector.[6]
Results from research projects and student assignments will demonstrate how such
changes can take effect when applied to façade construction. Different product
development approaches for various components of a system façade are offered that
were manifested in realised prototypes. Their potential in terms of being integrated
into a real production chain in the field of façade systems will be discussed in this
dissertation.
2
About Grasshopper: For designers who are exploring new shapes using generative algorithms, Grasshopper®
is a graphical algorithm editor tightly integrated with Rhino’s 3-D modelling tools. Unlike RhinoScript,
Grasshopper requires no knowledge of programming or scripting, but still allows designers to build form
generators from the simple to the awe-inspiring.
Reference [5]: Davidson, S. Grasshopper - Generative Modelling for Rhino. 2012 [cited 2012; Available from:
http://www.grasshopper3d.com/
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AM Envelope
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§ 1.2 Motivation
§ 1.2.1 Engineering
Since the end of the 19th century, the engineers who developed early architecture
and structures were trained to solve challenges and problems within a given range of
products and industrial standard parts. I-beams, rivets, bricks and other ’building’
materials led to a predetermined range of sizes, measurements and, therefore, to
repeating products. These circumstances led to the fact that the concept of ‘design for
production’ is deeply embedded in our manner of thinking. This limits the possibilities
of generating new constructions and new designs. We tend to fall back to the standards
that still surround us today.
Most of the standard tools today are subtractive. In contrast, AM is the first attempt to
think additive rather than subtractive. This leads to a whole new world of engineering
because there is no need to assemble existing parts that will be later combined into the
end product. We can start thinking about the performance we want to achieve with our
product first, and then begin to engineer the needed materials around this performing
feature. AM technology even allows us to engineer the parts integrally – for example
the functionality of a hinge could be derived from the material properties rather than
from fittings, bolts and joints added to the part. Additive methods allow for structures
that are not realisable with the traditional manufacturing methods. AM can integrate
complex functions into components without additional work expenditure. No longer
taking place at the construction site, the assembly is done in the virtual model.
Against this background it became obvious that AM could take engineering to a new
level. It was important to apply the technology in teachings and seminars to gain
deeper insight into its usability. For this new design approach, the term ‘Funktionales
Konstruieren’ (functional constructing) was introduced. We do not need to realise
constructions with existing standard parts, but we can digitally materialise the part
around its performance. This will gain in importance in façade technology, in building
construction and ultimately in architecture.
An increasing number of recent architectural projects exemplifies that the realisation
of visionary CAD designs (Computer Aided Drawing) is still coined by the limited
possibilities of technical realisation that exist today. Free-form architecture requires
expert knowledge. Thus, after creating a unified, homogenous overall design,
the structure must be divided into transportable small components. During the
21Introduction
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planning process the requirements for individual building parts such as roof, wall
and foundation are broken down into small components, only to be reassembled at
the construction site. The result is one large unit that, upon closer inspection, can be
broken down into its constructive parts.
Transition-free production, a true CAD-CAM workflow (Computer Aided Drawing
– Computer Aided Manufacturing) from such open CAD designs into the built
environment is not yet possible. AM technologies might be a solution to realise
freeform designs. However, since the AM manufacturers’ focus does not lie on
architectural applications, the development in this area has not exceeded the research
stage (see chapter 3 and chapter 4). In order to utilise AM technologies for building
construction, they must be designed for large applications.
a
b
c
d
Figure 3
a) Screenshot of FDM job preparation on the computer; software used is Catalyst: the 3D *stl. file after the import.
b) The 3D *stl. file after the slicing was done by the software.
c) In blue: the outline of the support structure; the first layer on top of the building platform.
d) In blue: outlines and filling of the support structure; in red: outline of the ABS part; in green: filling of the ABS part.
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AM Envelope
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§ 1.2.2 Background AM
Since there is an unlimited array of possible applications in all fields of the industry,
different AM technologies have appeared on the market since their invention in the
mid-eighties of the previous century. Some have already ceased to exist; others are only
starting to develop their full range of usage. What they all have in common is their great
potential for specific applications, for example in aerospace, the automotive industry
and medical application. AM is also becoming more and more popular in applications
for end use products. However, a lot of companies still use the technology primarily
for prototyping (fit and assembly, design studies) or pre-cast modelling rather than
for actual end use parts. But end use parts are the area of application to which this
technology is heading. It is important for architecture, building construction and façade
engineering to find suitable applications for the technology to be able to exploit the
potential as well.
Today, the most commonly used technologies in AM are Selective Laser Sintering (SLS
§ 2.2.1.2), Stereolithography (SLA § 2.2.1.1), 3D-Printing (3DP § 2.2.1.4) and Fused
Deposition Modelling (FDM § 2.2.1.3). They are all used to generate physical models
and parts from 3D-data without extra tooling, by adding building material layer by
layer and solidifying it [3]. A great range of materials offers the possibility to conceive
applications in many different product fields. Today, all of the technologies still only
use one or two materials at a time, except for the ‘Polyjet-Matrix’ technology by Objet
(§ 2.2.1.5) which started using ‘digital materials’ to produce gradient materials. [7][8]
Interconnecting the processes and enhancing material properties seem to be the crux
of the matter for an AM Envelope.
One major advantage of AM is the freedom of shape. Where the possibilities of
‘conventional’ tooling and manufacturing end (usually subtractive shaping methods),
AM offers new possibilities and even enhancement of products and tools. The high
standard that the processes have reached today also allows the metal-working industry
to notice AM not only for prototyping (mainly in plastics), but to appreciate it as a new
way to produce parts, even in metal. Direct Metal Fabrication (§ 2.2.3) - the name of
this particular field of AM – can be used with a great range of metals, and is therefore
suitable for façade applications.
The main focus of the research conducted as part of this dissertation was to identify
possibilities to transfer AM technologies to existing and future façade construction.
All aspects of its use as a production feature within the production line of the façade
industry were investigated: Applicability for existing façade systems, status of intuitive
usage, materials available for AM, potential for introducing AM as an alternative way to
fulfil non-standard façades.[9]
23Introduction
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With the increasing use of 3D applications, Additive Manufacturing also comes to the
fore of architects. The applications in this field are still limited to the generation of
printed 3D architectural models. But the advantages seen in modelling are the same
as for AM of real architectural parts or even entire buildings. This means production
without manual screwing, gluing, joining and fitting.
The new manufacturing technologies will change the way we design and manufacture
as well as how we deal with consumer goods and the built environment.[10]
Today, printed end use parts are not yet applied in building technology or architecture.
But printed end use parts are the field where an AM Envelope would push the limits.
§ 1.3 Hypothesis and sub-questions
The following hypothesis serves as a guideline for the scientific discourse of this
dissertation:
Façade technology and façade construction will change with the application of Additive
Manufacturing!
Since this hypothesis cannot be confirmed in one single statement, the dissertation will
generate, prove and answer relevant sub-questions; to highlight the current state as
well as to support the discussion about the target state.
Chapter 2:
• What technical possibilities for façade construction are available today with AM?
• Which changes do AM technologies have to undergo to be applicable to façade
technology?
• Which external influences can cause such changes?
• Which technical requirements are posed on an AM Envelope?
Chapter 3:
• Which research approaches lead to first experiences with AM technologies in the
building envelope?
• What are the effects of product-oriented project results on a general transfer of the
AM technologies to façade technology?
• What means of assistance for planners and users of AM must be generated in order
to guarantee AM oriented application in the façade?
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AM Envelope
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Chapter 4:
• Which developments of the AM technologies for façades are conceivable?
• Which façade applications can result from these developments?
• What effect can an integration of high-tech technologies have on building
technology?
Chapter 5:
• What is the potential of Additive Manufacturing for the building envelope?
The hypothesis focuses on façade construction. It is therefore clearly removed from
the more general examination of the effect of AM on building construction in general
and the influence that AM has on architecture in terms of design and appearance.
These more expansive aspects are touched upon in chapter 4. However, due to the
scope of the issue they are worth a separate dedicated discussion that is not part of this
dissertation.
The hypothesis was examined using examples from the field of façade application.
During the project phase, relevant data was acquired after immediate consultation
with an industry partner. The analysis of this data therefore represents the view of
future technology users (in this case façade manufacturers, façade builders) as well as
of product users (architects, planners, customers).
Next to the hypothesis, the sub-questions aid in keeping the discussion focused and in
illustrating the discourse. The sub-questions lead through the chapters and therefore
allow for contextual allocation. They support a scientific discussion and make it easier
for the reader to comprehend the content presented with regards to the main aspects
of each chapter and against the background of the overall subject matter. Chapter 5
links the questions to a possible timeline covering the next few years. It provides
concise answers and therewith rounds off the work.
§ 1.4 Approach and methodology
Because only few sources are available in the field of ‘façade/building technology
and AM’, this work was conducted as a qualitative study based on the self-chosen
hypothesis. The qualitative approach brings forth that the initial hypothesis evolves
into a strong, independent theory. During the scope of the work this can lead to
individual aspects gaining or loosing importance or to the inclusion or exclusion of
individual aspects.
25Introduction
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The potential of Additive Manufacturing for facade construction
Chapter 1
- Motivation
Research entry
Application in
Facade Construction ?
Chapter 2
- Demands „Facade Tech“
- AM-Technology
- AM-Materials
- feasibility
Case Studies
Chapter 3
- Guideline
- Engineering
- Findings
- R&D Projects
- Teachings
- Nematox I + II
- Thesis Supervision
Approach & Variations
Chapter 4
- Principles for AM
- Future Developments
- Chances
Changes in
Facade Construction !
Facade Approach
and Next Steps
- Evaluation of AM
- Future Application
Resume
Chapter 5
- Open Questions
- Potential
- Summary
AM Envelope
Figure 4
Structure of the dissertation (schematic representation of the work).
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AM Envelope
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A ‘multi-method scenario’ was developed as a source to acquire data and information.
With this scenario all contributing single parts flow into an overall collection of source
material. A large number of sources were generated during the course of the project:
•
•
•
•
•
case studies;
workshops and seminars;
discussions with experts (at tradeshows, conferences, project meetings, a. o.);
personally collected data by the author;
published data in various media.
The data from these sources combined with personal experience and reliable
(published) knowledge form the basis for the results presented in this work.
Following an introductory chapter, chapter 2 describes the current state of the art of
Additive Manufacturing. This serves as a basis to comprehend all relevant conceptual
approaches and questions of this work. At this point, the work does not claim to be all
encompassing because the development of the new technologies progresses so rapidly
that a representation can only show the current ‘status 2012’. This is particularly true
for § 2.5.1 which particularly highlights how fast the developments progress regarding
the process chamber and system dimensions. All technical information was collected
over a period of four years and was last updated mid 2012.
After the description of the technical aspects and topics as related to Additive
Manufacturing, chapter 3 provides a product-oriented description of the research
project. It forms the main part of the acquired data because the potential as well as the
limitations of AM technologies as they apply to the façade can be determined by means
of the projects and studies shown here. All data and findings related to § 3.3 through
§ 3.5 were generated in cooperation with the company Kawneer-Alcoa. The projects
described are the result of a mission oriented research conducted by the author at
Hochschule Ostwestfalen-Lippe (third party funded project “Influence of additive
fabrication on the development of façade components”, Hochschule OstwestfalenLippe, Fachbereich 1, Detmold, September 2008 through October 2010).
Summarising and evaluating the conducted case studies inevitably leads to
transferring the results to façade technology in general. This is introduced in chapter
3 by means of the project results, and leads to a catalogue of requirements for future
planning processes.
The described research approach should be continued; methods and ideas here fore are
described in chapter 4. The evaluation of the potential is then looked at and discussed
using realised and unrealised exceptional architecture. The current discussion about
design and appearance of architecture and the translation into built realisation is put
into context with AM.
27Introduction
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The summary in chapter 5 rounds off the dissertation and, at the same time shows
the steps necessary to continue this study and to apply Additive Fabrication to façade
technology. The potential of future development and application of the AM technology
in the building envelope is evaluated and put into context.
This work ends at a particular point in a dynamic process with the currently available
results relevant to the posed hypothesis. It does not claim to be complete or to provide
an ultimate evaluation of AM for façade technology. On the contrary, it challenges
to use the findings to continue the integration of the AM technologies. The building
sector in particularly needs a revolution to advance from the International Style with its
gridlocked and sufficiently celebrated results toward a regionally anchored, thought out
and manufactured architecture that fulfils today’s demands, and places the needs and
requirements of the user on centre stage.
References chapter 1
[1]
Knaack, K., Bilow, Auer, Façades. Principles of Construction. 2007, Basel: Birkhäuser Verlag AG.
[2]
Davies, M., A Wall For All Seasons. RIBA Journal, 1981. 2(88).
[3]
ASTM, Typologies for layered fabrication processes, in ASTM F2792, A. USA, Editor. 2009, ASTM International
Committee F42 on Additive Manufacturing Technologies: Annual Book of ASTM Standards, Volume 10.04
[4]
Hopkinson, N., R.J.M. Hague, and P.M. Dickens, Rapid Manufacturing. An Industrial Revolution for the Digital
Age. 2006, Chichister, England: John Wiley and Sons, Ltd.
[5]
Davidson, S. Grasshopper - Generative Modelling for Rhino. [cited April 2012]; Available from: http://www.
grasshopper3d.com/.
[6]
Strauss, H., Funktionales Konstruieren - Einfluss additiver Verfahren auf Baukonstruktion und Architektur, in
Fachbereich 1 - Lehrgebiet Konstruieren und Entwerfen. 2008, Hochschule OWL: Detmold. p. 136.
[7]
Woodcock, J., Living in a (Multi) Material World - Objet Focus on Democratizing Multi-Materials Process and
new functional materials, in tct magazin. 2011, Duncan Wood.
[8]
Objet Geometries. www.objet.com. [cited April 2012]
[9]
Strauss, H., AM Façades - Influence of additive processes on the development of façade constructions. 2010,
Hochschule OWL - University of Applied Sciences: Detmold. p. 83.
[10]
Wohlers, T., Wohlers Report 2010, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2010: Fort Collins, Colorado, USA.
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AM Envelope
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2 AM technologies for façade
construction
This chapter answers the following questions:
• What technical possibilities for façade construction are available today with AM?
• Which changes do AM technologies have to undergo to be applicable to façade
technology?
• Which external influences can cause such changes?
• Which technical requirements are posed on an AM Envelope?
This chapter explains the technical boundary conditions and the development
of Additive Fabrication and puts them into context. Expected performances and
developments related to an application in façade technology are formulated and
assessed. Factors and technical developments are described which, from the author’s
point of view have an impact on further development of the AM technologies related to
a transfer to building or façade technology.
Initial research into these technologies began as early as in the Sixties of the past
century, when tests were conducted to cure fluid photopolymers. This research
was then further developed by various institutes.[1] In 1987, the first system for
stereolithographic fabrication of plastic prototypes was integrated into the development
chain of injection moulded parts. The motivation behind this was the desire not to
discuss mass production of plastic parts as a mere thought construct and on the basis
of drawings only, but to be able to present a haptic representation of the design. This
application hits the core of the original term ‘Rapid Prototyping’ (RP), and shows the
immediate connection of this technology with a preliminary stage of mass production.
1:1 models of each developmental stage can be printed relatively quickly, meaning that
improvements can be integrated at any given time. This option simply did not exist
before due to the extremely high cost of the tools needed for the production process.
The materials as well as the technical equipment for AM technologies have been
continuously developed since. A new market opened up that is still growing today, 20
years later, and that brings forth new developments at ever shorter intervals.[1]
It was only during this ongoing development that the potential of ‘Rapid Prototyping’
in terms of changing the fabrication method of parts was recognised, and its use as an
independent production method was really considered. The step to use AM methods
to produce ready-to-use parts directly meant that ‘Rapid Prototyping’ evolved into
‘Rapid Manufacturing’ (RM) and thus the creation of the superordinate term ‘Additive
Manufacturing’ (AM).
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AM technologies for façade construction
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One issue still hindering the step forward to consequently realising the possibilities
that AM offers is the designers’ habits. Developing new products is always coined by
the existing boundaries of conventional manufacturing. Up until now, design ideas
had to be altered such that they could be manufactured with the equipment commonly
available (‘Design for production’). For example, the rules for moulded parts clearly
define the design process of such parts: technical restraints limit the freedom of design
in terms of demouldability, homogenous wall thickness, and integration of slide feeds
or split lines. With the application of AM this is no longer necessary since there is
almost no constriction of form and shape. Developers need to fundamentally change
their way of thinking in order to exploit AM to its full potential and to create true AM
constructions (‘Design for AM’).
§ 2.1 State of the art
The term ‘Additive Fabrication’ encompasses more than twenty different technologies
of layered production of prototypes, tools or series production parts.[2] The methods
differ significantly from subtractive methods that involve removing material. Additive
fabrication means fabrication without the use of tools or moulds – “tool-less”[3] - and
therefore allows for great freedom of geometry: With layered fabrication it is possible to
generate undercuts without having to remove material later which is not possible with
methods based on counter moulds (for example injection moulding). Projections as
well as cavities can be generated. It is no longer necessary to build massive, monolithic
parts with enclosed surfaces. Instead, integrated joints, articulating bodies inside
enclosed envelopes (‘sphere in a sphere’), or contour-conform channels (to cool tools
during mass production) can be realised. AM enhances the conventional methods
with this constructive freedom. It goes beyond the hitherto feasible and is significantly
different from the known methods (see [3] [4] [5] [6]).
The technology is used by designers and manufacturers in the areas of product design,
consumer goods, industrial goods and medical and military applications. Products
produced with layered construction include: protective covers for mobile phones,
games consoles parts, designer lamps, machine parts, chassis and drive parts for
airplanes and automobiles, tool elements, medical implants and many others
(see [7] [8]).
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§ 2.1.1 The principle of additive processes
The principle of Additive Manufacturing is the same for all of the different methods:
special computer software breaks the Computer-Aided-Design (CAD) 3D model down
into layers. These layers form horizontal layers/building plans/foot prints of the model.
The breaking down process is called slicing. The AM output device (in the following
also called ‘printer’) processes each layer of the model consecutively, whereby the
contours and fillings of the part are cured. Depending on the method, this is done by
either exposition, heating, or bonding in process chamber which typically is confined
to certain dimensions. Different technical strategies are used to bond each new
layer with the previous one. Thus, layer by layer, the physical representation of the
virtual CAD model is generated. “With these methods [… AM methods, author’s note]
fabrication is not conducted subtractive from a massive body, such as with milling, but
generatively (additive), i. e. the parts are created in layers by adding material or by the
phase change of a material from a fluid or powdery state into a solid state. Fabrication
is done without the use of moulding forms”.[6] One single model can consist of several
hundred layers, depending on its size. The layer thickness is defined by the resolution of
the AM system used; it varies from several tenth of a millimetre down to a few microns.
Once the building plan for the model has been fully processed, the completed model
can be removed from the machine. The process can take from a few hours to several
days. Depending on the technology applied, the actual ‘printing’ process is followed
by various subsequent processes (post processing) such as removal of support fixings,
surface cleaning, removal of uncured material, infiltration, and others.
a
b
c
Figure 5
a.) CAD model; b.) slicing process; c.) building process.
If AM is compared to conventional printing methods, each layer corresponds to one
page of a document to be printed. The only difference being that you do not print
on paper and not exclusively with ink. The finished product is a physical, threedimensional rendition of the virtual computer model.
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AM technologies for façade construction
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§ 2.1.2 Materializing a 3D modell
To generate a 3D model, a third, the vertical Z axis is needed in addition to the two
horizontal axes (X and Y). Movable printheads or redirected light beams extend across
the horizontal extension of the model. Hereby, we differentiate between vector-oriented
and raster-oriented methods.[6] Building the model up in direction of the Z axis is done
by incrementally lowering the work platform. “Depending on the individual methods
used, different levels of accuracy and part properties occur along the three coordinates.
This needs to be considered when aligning the part in the process chamber. Building
time is another factor that depends on the positioning in the process chamber.
Some methods require supports when generating parts with protruding geometries
[…, or in order to connect planes to the substrate plate when producing metal parts,
author’s note]. They need to be mounted before the manufacturing process begins and
usually have to be manually removed once it is completed. The system user generates
the supports by using options in the system software or separate software tools.
With some methods, using supports reduces the surface quality of the part, a fact that
cannot be avoided entirely. It is therefore necessary to mark the areas where supports
may not be placed.”[6]
§ 2.1.3 Surface quality
The surface finish depends on the type of manufacturing process and the materials used.
Thus, the user can influence the quality of the manufactured parts. With most systems,
the user can select from different levels of resolution as well as change the parameter
‘scanning speed’ and ‘laser intensity’ for those systems using a laser for curing.
But as a general rule, most methods generate a stepped surface because the part is
produced in layers.
Figure 6
Schematic drawing of an FDM method and surface steps depending on the model contour.
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AM Envelope
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Even in 2012, the addendum ‘rapid’ is a relative term in conjunction with AM methods
because an actual production process may take up to several days. However, the
equipment development has reached a stage where the combination of processing
speed and material properties does achieve ‘fast’ effective manufacturing rates when
compared to traditional methods. This comparison takes into consideration the time
it takes to produce a conventional tool set (for example for injection moulding) for
traditional methods. But speed is not the most important aspect when evaluating
AM technologies. The main advantage lies in the great freedom of form compared to
traditional methods. Thus, it is not cycle time alone that is important when evaluating
processing methods but also process optimisation, process controllability as well as
product and quality optimisation. As an example, optimised Rapid Tooling tools can
not only optimise the manufactured product but the manufacturing process as well.[9]
Additional applications and markets have evolved from the original, generative method
Rapid Prototyping (RP) resulting from an improvement of materials and equipment:
Rapid Manufacturing (RM) and Rapid Tooling (RT). In the following, they will be
described in more detail because the superordinate term Additive Manufacturing
has evolved from these methods. Particularly in terms of transferring them to façade
technology, aspects from all three original segments play a role.
§ 2.1.4 Rapid Manufacturing
Rapid Manufacturing (RM) means using Additive Manufacturing methods to produce
ready-to-use products without the need to invest in tools. Critical factors are ‘time to
market’, ‘batch size 1’, ‘product and manufacturing cost / cost efficiency’ and ‘product
testing before production’. RM is a unique service segment in the AM industry. Parts,
design objects, small batch series amongst others are manufactured to order with a
pool of AM equipment. RM with its significant design and production benefits can be
seen as a new, separate market. Advantages gained through cost savings for tools (no
customized tools, no casting moulds), new sales strategies, the impact on product
development and design indicate the great potential this technology offers.
RM describes the professional use of AM technologies in an industrial production
chain. Here, the technology is used to produce small series and combines continuous
product optimisation with the additional benefits of manufacturing with AM.[10]
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AM technologies for façade construction
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Figure 7
Jewellery part designed for AM by FOC, Amsterdam.
Figure 8
Lighting Design with AM by FOC, Amsterdam.
§ 2.1.5 Rapid Tooling
Rapid Tooling (RT) describes the application of additive methods for manufacturing
production tools for mass products. The industry exploits the possibilities of CAD
design combined with the unlimited freedom of form of AM. For injection mould
nozzles to manufacture plastic parts, for example or for models of casting moulds or
the casting moulds themselves. The advantage lies in eliminating the limitations of
traditional subtractive methods for tool making. Free-forms, contour conform ducting,
undercuts a. o. are no longer difficult to manufacture. The great range of materials
available today allows us to directly create metal tools and use them for production.
These tools equal their traditional counterparts in toughness, duration and utilisability.
And not only that: material properties can be further improved by better cooling and
the possibility of a targeted material mix.[7]
a
b
Figure 9
a) Tool with integrated cooling channels; b) Illustration of contour conform cooling channels.
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§ 2.2 Overview of the most common AM processes
Since 2009, all categories of the layering methods are summarised under the
superordinate term ‘Additive Manufacturing (AM)’. This regulation is the first
universally valid agreement in the AM industry and was manifested by the regulation
of the American Society for Testing and Materials (ASTM), committee F-4291,
publication F2792, 09/2009. This standard defines AM as “AM: ~ process of joining
materials to make objects from 3D model data. Additive Manufacturing (AM) as
opposed to subtractive manufacturing methodologies. Usually with AM parts are
processed layer upon layer. Synonyms: additive fabrication, additive processes,
additive techniques, additive layer manufacturing, layer manufacturing, and freeform
fabrication.”[11]
For the German speaking areas, the ‘Verein Deutscher Ingenieure’ (VDI - Association of
German Engineers) has published Norm 3404 to regulate the terms and applications
of Additive Fabrication. The norm was introduced in 2009. The norm includes “fieldproven tips and recommendations” in order to “improve the communication between
customer and supplier and thus to support a binding services format and trouble
free execution”.[6] The efforts of VDI need to be viewed against the background of
an increasing integration of the AM technologies into production processes and the
according demands for standardisation and regulation.
During recent years, the term ‘3D printing’ has become a widespread general term
for additive methods, independent of specific technology, material and intended
application (RP, RM, RT, or AM). When talking about these methods, it is therefore
important to differentiate between the actual technology (3DP § 2.2.1.4) and the
general term of ‘3D printing’. Typically, non professional media uses ‘3D printing’ as
the common term, which encompasses professional AM systems as well as ‘fabbers’
(appendix A I / Fabbing), systems usually used in a non-professional environment3.
3
“A fabber (short for “digital fabricator”) is a “factory in a box” that makes things automatically from digital data.”
Reference [2]: Burns, M. fabbers.com. 1999-2003 [cited April 2012]; Available from: http://www.ennex.
com/%7Efabbers/.
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Considering the goal of transferring the layering principles to façade technology,
it makes sense to make an initial differentiation between the individual methods
depending on the building materials used. This also facilitates the introduction into the
multitude of technologies. The material groups used are ‘plastics’, ‘metals’, and ‘other
materials’. In an AM family tree they are linked to the according available AM method.
The great number of available technologies can be traced back to the first additive
method – SLA. All of the following technologies are based on the same manner of
thought; building up the shape of the part layer by layer. Plastics as a material group
with the according processing methods are at the centre of the development. Some
can, again, be understood as a superordinate term for which different manufacturers
have developed systems based on the same technology. In the field of plastics, the core
technologies are Stereolithography (SLA § 2.2.1.1), Laser Sintering (LS § 2.2.1.2),
Fused Deposition Modelling (FDM § 2.2.1.3), 3D Printing (3DP § 2.2.1.4), as well as
the methods combined under the term (InkJet § 2.2.1.5).
In addition, methods to process metals were developed, mainly evolving from the
application Rapid Tooling. This development is influenced by SLA as well as build-up
welding which is a known and proven technology in machine and plant engineering. All
technologies are evaluated in a matrix in terms of their relevance for façade technology,
and are compared at the end of the chapter.
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AM Envelope
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Familiy Tree of AM
SLS
Casting Cores
ProMetal
- for large scale
Metal casting
VoxelJet (3DP)
- for large scale
Metal casting;
- e.g. boat-engines
Contour Crafting
Big Scale AM
Other Materials
- fast curing, fibre
reinforced concrete
- marble powder
D-Shape
PolyJet
Ink Jetting
M3D
3DP
3DP
VoxelJet
fabbing
FDM
- RepRap
- [email protected]
- fabbaroni
- Makerbot
FDM
Background: Additive Fabrication
- large scale SLA;
- e.g. prototyping for dashboards
Mammoth
Stereo Lithography Apparatus
(SLA)
DLP
SLA
SLA
SLS
SLS
Plastics
High Speed SLS
DMLS
Metalls
SLS
powder bed
processes
LaserCusing
SLM
EBM
ProMetal
3DP
powder feed
processes
Background: Industrial Standard Fabrication
Build-Up Welding
(Auftragsschweissen)
- for jewelery
in Gold
AM processes
from welding
powder feed/
wire feed
process
- for green parts;
- intermediate use!
LENS
- sold as DMDS
DMD
- developed from
Laser Metal
Deposition (LMD)
CLAD
- in combination
with CNC milling
EBF³
- U.S. Army
„Mobile Parts Hospital“
Figure 10
Family tree ‘AM methods’.
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AM technologies for façade construction
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§ 2.2.1 AM for plastics
The following describes only a few selected technologies to provide information about
the basic principles of Additive Fabrication. After analysing and evaluating all methods,
the performance aspects described here allow us to understand the relevant AM
methods for façade technology.
Further information about the technologies (those briefly described here and others) can
be found in the appendix A I / Characteristic tables of AM processes – plastics.
Note: The schematic sketches for the individual methods are based on Hopkinson et al.
[3], but were redrawn and modified by the author.
The primary decisive criteria to estimate the potential of the technologies for their
application in the façade technology are weight, rigidity, and load-bearing capability
of the parts. Therefore, the focus of the technology descriptions will also lay on
the methods to produce metal parts, even though, from a technical point of view
they evolve from those used to produce plastic parts. For easier understanding, the
descriptions are therefore based on the historic or content-technical development
within Additive Fabrication.
§ 2.2.1.1
Stereolithography
Stereolithography (SLA) means curing thin layers of a light sensitive, fluid
photopolymer with a light source. Laser or halogen lamps can serve as light source.
The part is generated in a bath of epoxy resin or acrylic resin. The light source traces
the layers of the computer model; the resin is locally cured by the light source. To print
overhangs, undercuts and filigree model parts, SLA requires an additional support
structure. This is generated by the system software automatically analogous to the part.
When a layer is traced, the work platform is lowered by the selected layer thickness,
and the surface is reflooded with resin. To improve wetting the model surface with
new resin, the resin is heated to 30° to 40° Celsius, which decreases its viscosity. The
temperature has no influence on the light exposure during the polymerisation process.
In a post curing process, the model runs through a light chamber to guarantee
complete curing of the material. Thus, areas that are not fully exposed are also cured.
The supporting structure must be removed mechanically after curing.
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The surfaces of the part can then be post-processed by polishing, blasting, or coating.
SLA methods allow for a high possible part accuracy. The layer resolution lies between
0.05 and 0.15 mm.
In order to be applied to an AM application, issues in terms of resistance to ultraviolet
rays and humidity must be solved. Targeted further development of SLA materials
shall achieve an even broader applicability of the SLA method in terms of direct
serviceability.
Figure 11
Schematic drawing: SLA method
39
AM technologies for façade construction
Figure 12
Lighting Design produced with SLA
i
§ 2.2.1.2
Laser Sintering
In principle, with laser sintering (LS) the part is created similarly to SLA methods.
However, a specified powder is used as building material rather than fluid resin.
Figure 13
Schematic drawing: LS method
Figure 14
Sample piece produced with LS
Related to AM, the term sintering means: to melt powders below the actual melting
temperature. The energy of the light source on a compact mass causes the material to
melt (see [1] [35]).
After one powder layer is sintered, more powder is deposited onto the work platform,
creating the next layer. Infrared light keeps the entire process chamber just below
the temperature of the sintering process, within the so called crystallisation range of
the material. This method keeps the energy demand of the actual process low; avoids
warpage of the parts caused by abrupt heating, and improves the fusion with the
previous layer.
The light source must only heat the material by a few degrees in order to melt it.
The non-sintered powder around the model remains as supporting material. Upon
completion of the process it is returned to the storage container of the machine and
can be reused when mixed with new powder.
LS allows for wall thicknesses of 0.8 mm. The layer thickness of the powder bed is
usually around 0.1 mm.
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AM Envelope
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In contrast to SLA, LS does not require an additional curing process. But the finished
parts need to cool down before they can be ‘unpacked’ from the LS machine. As the
surface finish is porous, these structures sometimes require an infiltration with other
materials, depending on the application.
§ 2.2.1.3
Fused Deposition Modelling
Fused Deposition Modelling (FDM) is a ‘true’ additive method since the material is not
cured or glued but actually deposited onto a work platform in layers.
Figure 15
Schematic drawing: FDM method
Figure 16
The visible structure of the different layers after
completion of the FDM print job. In white: the ABS
material; in brown: the soluble support structure
As with the SLA technology, the layers of the 3D data file are deposited consecutively
on a work platform. The material is melted at approximately 280°C, applied with an
extruder (a melting nozzle similar to the principle of a hot-glue gun) and cures directly
onto the underlying layer. To ensure that the individual layers bond to one another, the
entire process chamber is heated to and maintained at a certain temperature. Too early
curing could prevent a new layer bonding with the previous one.
A supporting structure is necessary because the models are generated directly on the
building platform. It supports overhangs, undercuts, filigree model parts and wall-like
areas that are not self-supporting before cured. The support structure is generated
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AM technologies for façade construction
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automatically by the software and deposited through a secondary nozzle using a special
support material. The support material is removed from the finished product either
mechanically or in a solvent bath.
For each layer, the exact positioning of the string of material can be previewed and
controlled with the software. The outer contours of the component are printed first,
and then the remaining areas are filled in completely or following a grid pattern. The
strings of material are positioned such that the shape is filled in precisely according
to the contour. The cavities between the walls of the model are specified in order to
control the processing speed, the material consumption and the density of the model.
The geometry and the properties of the string of material result in model surfaces and
edges with a stepped contour. This fact defines the limitations related to accuracy and
surface finish of the method. The layer resolution lies between 0.127 and 0.330 mm.
Due to the very anisotropic structure of the material distribution, FDM technology also
creates strongly anisotropic parts. The material properties are significantly better in
X-Y, meaning in the ‘full’ material, than in Z where the fusion of the individual layers
determine the properties of the part. Therefore, this technology is only partially suited
to produce parts that are subjected to long-term stress.
FDM models can be finished by various methods.
§ 2.2.1.4
3D-Printing
3D printing (3DP) can be compared to inkjet printing on paper. The layers of the 3D
data file of the model can be compared to the pages of a document. Equivalent to inkjet
printing on paper, each layer from the data file is identified as one page and is printed
onto a thin powder layer with colour pigments (colour printer cartridge) and a ‘binder’.
The materials used are gypsum, starch, ceramic powder and sand. The binder is
an adhesive that fuses the powder (and the ink) to a solid mass and glues it to the
underlying layer. After one layer of the building plan has been printed, the work platform
is lowered by the thickness of one layer, a roll or slider deposits a new layer of powder,
and the next layer can be printed. The layer resolution lies between 0.09 and 0.1 mm.
In this process, the unprinted powder serves as supporting material and is returned to the
system. Overhangs, undercuts, filigree model parts and wall-like areas that are not selfsupporting before cured are supported without having to print an additional structure.
Upon completion of the process, powder residue is removed with a fine compressed air
jet or a brush, and the surface of the model can be infiltrated with epoxy resin or instant
adhesive, if necessary. 3DP models can be finished by sanding, filling, varnishing,
polishing or galvanising.
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Figure 17
Schematic drawing: 3DP method
Figure 18
3DP part with representative colour coding of a FEanalysis
By using a colour cartridge, 3DP achieves true colour rendition; it is the only method
that offers the possibility of multi-colour printing.
Therefore, this method is used for realistic renderings of surface finishes and colours,
labelling, company logos, as well as simulated temperature, stress or deformation
gradients from Finite Element Analysis (FEM).
Illustrating geological information (GIS) is another application of 3DP. Complex
three-dimensional geological ‘maps’ can include more information than conventional
repro products.
3DP models are also used as intermediate products for further use in printing block
fabrication and moulding technology. The powder material for this process consists
of silica sand bonded with an inorganic binder. The results are fragile casting cores
that are used to fabricate metal casting moulds. Foundries have recognised the 3DP
method as an opportunity to generate geometrically demanding parts directly from
CAD data. All of the necessary supply and exhaust lines, lifting and fixing points are
integrated directly in the CAD model.
Systems with process chambers as large as 4 x 2 x 1 metre have been built to produce
casting cores for large ship’s engines and body parts.
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AM technologies for façade construction
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§ 2.2.1.5
PolyJet
The term ‘Inkjet’ combines those processes that use a series of printing nozzles instead
of one printhead or a specific light source and mirror device. Highly viscous plastics are
used as building material, as the coloured ink for desktop inkjet printers.
With the PolyJet™ method, the layers of the part are created with individual drops of
material that are deposited onto the work platform. The printhead holds numerous
nozzles that are arranged across the width of the platform. The light source for curing
the material is mounted directly behind the print nozzles. The model area along the
X axis is covered by the nozzles; the printhead runs along the Y axis, the so-called
pass. Building up the height of the model is achieved by lowering the work platform.
Immediately after one layer is complete, the deposited material is cured with ultraviolet
light. In a secondary step, a roll smoothes the layer surfaces, onto which the next layer is
deposited during the following pass. All of the material needed for one layer is pushed
out of the nozzles simultaneously. The material used is an acrylic photopolymer. The
necessary support structure is printed with a secondary row of nozzles. It consists of a
gel-like material that, after completion, is removed by water jetting.
The layer thickness is about 0,016 – 0,030 mm and guarantees a very precise and
smooth surface; eliminating the need to rework for most applications. Since the
material is deposited in individual particles, the final resolution is very high.
Figure 19
Schematic drawing: PolyJet™ method
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AM Envelope
Figure 20
PolyJet process during the UV-light curing of the
plastic material on the building platform (below).
i
With the PolyJet technology it is possible to mix numerous gradients of the two original
materials directly onto the process platform, using so-called ‘digital materials’. Thus,
different areas of the part can feature different material properties. We know this from
handles with hard as well as soft parts, for example, or remote controls with a hard
casing but soft buttons. This is of great advantage for realistic prototype production (for
example for flexible joints, rubber soles, springs a. o.). Even though it is not yet possible
to print the materials in a true gradient, meaning with seamless transition, current
technical feasibility already points toward the next step: programming true seamless
gradient materials (see § 2.4).
§ 2.2.2 Consumer applications
The increasing trend of consumers handling digital media and tools leads to a
constantly growing demand to produce individualised products. AM allows us to ‘print’
individual avatars from virtual worlds and online games, data records for various
everyday items are exchanged on online platforms. Thus, there is a growing desire
to produce commodities from self-generated or purchased data – ’fabbing’. In this
context fabbing is derived from ‘fabricating’ and describes generative manufacturing
of finished products; Such as customised toys, mobile phone or games consoles
enhancements, jewellery and design objects, sport equipment and spare parts for
products of all sorts.
Again, RM is the originating technology behind this trend (for further information
about the fabbing technologies see appendix A I / Fabbing).
Another branch of Additive Fabrication has developed as part of these home
applications: There are a number of different kits and instructions available to make
low-cost 3D printers for home use (‘fabber’ or ‘personal fabricator’) beyond those
available from commercial suppliers (see [4] [13]).
The kits are based on freely available software and hardware. The user community
also exchanges further developments on the internet, thus fine-tuning and technically
optimising these systems from generation to generation. The principle technology of
these systems is based on the above described AM technologies, mostly FDM, which
are broken down to the feasible technical minimum. In terms of performance the
fabbers sometimes equal professional systems: they achieve high resolutions and
accommodate various materials.
45
AM technologies for façade construction
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Figure 21
Not yet assembled RepRap kit; Hochschule OWL 2012
Figure 22
Self-assembled RepRap; FH Darmstadt 2010
Fabbers are mentioned here for the sake of completeness. In the context of this
dissertation, they obviously do not lead to optimised or modified building technology
with AM, but they do illustrate an increasing spread and usage of digital tools and
AM methods, even for ‘technological laymen’. For the future this means a growing
acceptance of digital methods, which will play an ever greater role in our daily lives.
§ 2.2.3 AM for metals
Direct fabrication of metal parts is called Direct Metal Fabrication (DMF). The
processes described in the following were initially intended for Rapid Tooling (RT);
however, the trend goes toward using them to manufacture ready-to-use products.
We can differentiate between two basic principles: ‘powder feed process’ and ‘powder
bed process’. Both use pure metal powder to manufacture parts whereby different
material mixes and alloys are employed.
To generate metal parts, the materials are melted by applying heat. The energy
sources are laser or electron beams. In order to achieve a controlled process, the
resulting waste heat needs to be carefully directed. For almost all DMF methods,
the models are manufactured on base plates (substrate plates) with a thickness of
up to ten millimetres. The base plate is clamped inside the system and the model
is then generated on this plate. In addition to the contour of the model serving as a
heat conducting element, a support structure is needed to direct the waste heat. This
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requires more intensive data preparation than creating plastic models. If the heat is not
properly exhausted in one area of the part, the result is a melting bath accumulation and
the model is caked with the surrounding material powder (material adhesion, defects).
In addition to the issue of heat development within the part, tensions that can develop
in a part are decisive criteria for success or failure with the DMF methods. Therefore
support structures ‘connect’ the part to the substrate plate. This eliminates warpage,
distortion and bending in Z direction. With powder bed processing, the worst case
result of such distortion can cause abortion of the building process, because the
wiper to smooth the subsequent material layer can get caught on the part. The part
can get repositioned and detached from the substrate plate. The necessary support
or connecting structures are challenging in terms of the surface quality of the directly
manufactured parts. After removing the supports, unevenness and therefore reduced
surface quality is unavoidable. That might prove problematic when working with
enclosed bounding geometries. Currently, there are two strategies that can eliminate
the limitation caused by the needed supports: Firstly, metallic materials are developed
for AM methods other than the ones currently available, and secondly, the concept to
manipulate the files prior to manufacturing in a way that they accommodate expected
deformations and thus generate the actual targeted geometry.[16]
But as of now these limitations are still part of manufacturing metal components.
[3] [14] [15]
Figure 23
Support structure (light grey) of a DMF part (dark
grey) after separation from substrate plate, @FKM
Sintertechnik GmbH
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AM technologies for façade construction
Figure 24
Inside view of DMF part: connective points of the now
removed support structure
i
1
2
Two strategies are conceivable to avoid reduced part quality:
The support structures are integrated into the part geometry at the very beginning of
the design process, i.e. a specific part orientation and part geometry can avoid that
defects of the outer contours are visible after the manufacturing process is complete.
And support structures in the form of lightweight fillings can remain within the part; a
method that can be used to further improve the performance properties of the part.
Very exact material parameters are used in order to avoid warpage or deformation, and
therefore allow for ‘Anchorless Selective Laser Melting (ASLM)’. To apply ASLM, it is
necessary to define new material properties from specific metal alloys and mixtures.
Eutectic metal alloys are used for ASLM that have a very precise melting point. With
ASLM the material behaviour during and after melting is controllable, therefore no
anchors are needed. This approach of ‘support free DMF’ is currently under research at
Loughborough University in England. First results are available; however, it is too early
to transfer them to general DMF methods.[16]
For DMF, the models are divided into different levels (shells). By using heat sources
with different intensity levels, different material densities or structures can be
generated for the individual shells. This is particularly important for lightweight design
because lightweight structures can be created inside closed components when using
lattice structures or ‘hatches’.
Figure 25
DMLS support structures still attached to the part and substrate plate.
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AM Envelope
Figure 26
DMF part of a turbine with internal honeycomb
structures, by ‘layerwise’ @ RapidPro2012, Eindhoven
i
Once the process is completed, the finished DMF model must be separated from the
base plate; with some methods by wire-cutting, with others the support structure can
be removed manually by means of simple tools.
Powder feed process
For the powder feed process method (also Fused Metal Deposition method), an energy
source (laser, electron beam) generates a melting bath on the surface of the model.
Metal powder is then blown into the melding bath through one or more nozzles.
With this method, the axes for energy source and inserted material run unidirectional.
The quality of the material joints within the model or on a carrier material (in case of
repairs) can be compared to that of a welded seam.
Only powder feed process methods offer the possibility to use different materials in
varying quantities in the same work step. To do this, different powders are transferred
into the melting bath via different nozzles.
All powder feed processes evolved from the application of repairing defect or worn
tools or parts (bearing shafts of large engines, turbine parts). The industry has known
this method for quite some time under the term build-up welding. It allows rebuilding
worn-out areas in layers, using the original building material. During post-processing,
surfaces that are too inaccurate for mechanical engineering must be turned or finished;
this is done with conventional methods such as CNC milling, sanding, polishing, and
eroding. Since all components that need to be true to size must be reworked, the power
feed process is a questionable method for complex parts. The advantage of tool-less
manufacturing is therefore annihilated.
The method does not create a support structure.
§ 2.2.3.1
Laser Engineered Net Shaping
Laser Engineered Net Shaping (LENS) is one of the first technologies in the series of DMF
methods; many other methods are based on this technology. The printhead consists of
a central nozzle for the energy source and material nozzles that are arranged around it in
a radial fashion. The head can be mounted onto different base systems as well as affixed
to a robot arm. The part rotates in front of the nozzle whereby the material continuously
builds up in the melting bath. The layer resolution lies at 0.500 mm.
The possibilities of using various materials in one component offers optimum
exploitation of the material properties for tool making, particularly in terms of
temperature behaviour and raw material cost. The method is used for repairs (machine
49
AM technologies for façade construction
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turbine blades), to coat base bodies made of low-cost metals (the protective coating
adds value), and to directly produce free geometries built in a base body.
§ 2.2.3.2
Direct Metal Deposition
Direct Metal Deposition (DMD™) is a direct successor of (laser) build-up welding;
the method is also known as Laser Metal Deposition (LMD). It is a generative laser
technology that deposits metal onto existing tools and components in layers. The layer
resolution lies at 0.1 to 1.8 mm.
Pure metal powder as the source material is sprayed into the CO2 laser melting bath
in particle form. Using pure metal offers a material density of 100%. The laser tip is
mounted on a five-axial CNC robot, so that the metal layers can be deposited threedimensionally. The material is stored in four chambers from which it can be mixed
or used alternately. DMD™ was developed to repair industrial tools and to refine tool
surface finishes. The combination with ceramic or non-metallic materials can lead to
optimisation of the tool properties such as abrasion resistance and extended lifetime.
In Rapid Tooling, this advantage is used to coat base tool forms made of copper with a
protective layer of hard tool-steel. Thus, conductive copper can be used for tool making
even though the material itself is too soft for a tool’s usage. Rapid cooling of the tool
after production enables fast reuse and thus faster production.
Since DMD™ is an additive method, worn tools can be rebuilt with the original material.
After depositing additional material, the surfaces can be further processed with
conventional methods. Today DMD™ is also applied in the field of RM. By processing
different materials, DMD™ might be used to produce Functionally Graded Materials
(FGM § 2.5.2.1 Functionally Graded Materials).[17]
§ 2.2.3.3
Electron Beam Free Form Fabrication
Electron Beam Free Form Fabrication (EBF3) combines various elements of the here
described methods into one laser based deposition method which uses a firm metal
wire for material supply. Systems for this method also feature an electron beam gun
(see EBM method, Arcam). The method can therefore be differentiated from the other
powder feed process methods, particularly due to lower energy consumption compared
to the use of a laser. A vacuum is applied to the process chamber during processing.
Components must be reworked with subtractive processes.
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§ 2.2.3.4
Construction Laser Additive Directe
Construction Laser Additive Directe (CLAD) systems use a powder feed process to
build up three-dimensional geometries. Combining this with specialised software
and a three to five axial CNC system to move the printhead makes it possible to create
components with a high degree of free-form shaping. Hereby, the “laser cladding”
method correlates to build up welding; it evolved from applications for repairing
machine parts. The layer thickness resolution lies between 0.10 and 1.20 mm.
Figure 27
Parts produced with the CLAD system; surfaces are still rough and need to be post-processed
Powder bed process
For the following methods the 3D model is generated from a powder bed of metal
powder similar to the SLS method. But contrary to laser sintering of plastic powder,
metal sintering includes transferring the process heat into a base substrate via the
model contours and support structures. Even though a large number of different metal
powders is available, currently only one powder type can be processed at a time.
The non-molten powder creates the support structure, and excess material is fed back
into the production cycle after printing. In contrast to plastic materials, there is no
tiring of the powder caused by heating. Therefore the powder can be reused without the
need to add new material.
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AM technologies for façade construction
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§ 2.2.3.5
Selective Laser Melting
The development of systems for Selective Laser Melting (SLM) went in a completely
different direction as, from the beginning on it was focussed on processing metal
powders. The systems can also process reactive metal powders such as aluminium and
titanium because inert gas was used early on to create a protective atmosphere in the
process chamber. Due to its technological edge, this type of system is still cutting-edge
amongst the metal powder processes.
The resolution of the layer thickness lies between 0,20 and 0,10 mm.
Figure 28
System by SLM-Solutions, method: Selective Laser Melting (SLM) SLM 280 HL; Imagery courtesy of SLM-Solutions.
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§ 2.2.3.6
LaserCusing
LaserCusing is an AM system that uses different metal powders, such as aluminium,
titanium, stainless steel and other alloys to produce AM parts. The powder is laser-melted
at a density of 100% and without adding any other substances. The entire amount of
unused powder can be used for further processing without compromising quality.
Inside the LaserCusing system the substrate plate is fixed with an industrial standard
fixation system. This allows the use of different CNC machines on the same part, as the
mounting system always delivers defined reference points for the part. This for example
allows a hybrid fabrication of CNC milled and AM printed parts.
The layer thickness resolution lies between 0,20 and 0,50 mm.
The term “Cusing” is derived from the first letter of the company name Concept Laser
and part of the word fusing.
Figure 29
LaserCusing system with mounted substrate plate, @
FKM Sintertechnik GmbH
53
Figure 30
Substrate plate for LaserCusing process with built upon DMF part on it, @
FKM Sintertechnik GmbH
AM technologies for façade construction
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§ 2.2.3.7
Electronic Beam Melting
In principle, the Electronic Beam Melting (EBM) method resembles the LS method; the
difference being that it employs an electron beam instead of a laser. An electron beam
gun generates an electric arc to melt the metal powders. The energy generated melts
the powder into the model at the powder bed surface. This is done under vacuum at
an operating temperature of approximately 1000° Celsius. Metal parts produced with
EBM show a higher level of melting-through than sintered parts. The cooling process is
precisely controlled in order to achieve accurate cooling of the fabricated metal parts.
The parts’ density lies at 100%.
When using this method, the components need to be reworked since the surface
finish quality is not high enough for all applications. Rework is done with conventional
methods such as sanding, turning, milling, and blasting. The layer thickness resolution
lies between 0,50 and 0,10 mm.
EBM can create durable yet very light-weight structures. In combination with
biocompatible materials they are used for implants, and for manufacturing of
components for the automotive and aerospace industries.
Figure 31
DMF hip implant made from titanium; fixations and a
rough structure for the bone material to grow inside
are provided directly from the CAD file. Customised
part sizes are available.
54
AM Envelope
Figure 32
DMF part in titanium; part height is ~ 20mm;
the rough surface is clearly visible and shows the
challenges for end use parts.
i
§ 2.2.3.8
Direct Metal Laser Sintering
The system technology for Direct Metal Laser Sintering (DMLS) has directly evolved
from SLS. Instead of plastic powder, metal powder is sintered in the process chamber.
Even though the DMLS method was initially developed for Rapid Tooling (RT), it
remains an accepted method within AM. Because of different requirements in terms of
surface quality, models might need to be reworked (milling, turning, sanding, blasting).
The layer thickness resolution lies at 0,20 mm.
The DMLS method is used to produce components for tools or machines as well as end
use products.
§ 2.2.4 AM for large scale structures
In addition to the known systems introduced here, there are additional approaches
in research and development. The two methods described here are characterised
by translating principles from the above described AM technologies; however,
the difference lies in the scale compared to the commonly used methods. They
are particularly interesting against the background of a possible transfer of these
technologies to architecture.
§ 2.2.4.1
Contour Crafting
Contour Crafting (CC) generates large structures made of fibre reinforced highperformance concrete. The building material is printed in layers through a nozzle,
while, at the same time, the lateral surfaces are smoothed with a trowel.
This is accomplished with a printhead that is mounted onto crane rails. Thus, the
system dimensions can easily extend beyond 6000 x 6000 x 6000 mm. Resolution is
several centimetres and depends on the nozzle used.
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AM technologies for façade construction
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Figure 33
Size of a Contour Crafting wall in comparison to a
human being, Imagery courtesy of B. Khoshnevis.
Figure 34
Contour Crafting ‘nozzle’ to generate concrete
parts with internal light-weight structures, Imagery
courtesy of B. Khoshnevis.
CC is an independent parallel development of the additive methods, since it is not
immediately based on one of the above mentioned technologies, but was a separate
development from the start. The principle of the generative build-up in layers is
the same as for the already described AM methods. However, due to the vision and
dimension involved it does assume a special position. System dimensions and the
intended results are significantly different.
CC is certainly an important factor when examining the technological developments
for architectural applications. The clearly formulated goal is the additive, automated
fabrication of “homes”, and is therefore a direct reference to architecture in general
and the façade in particular. Further development needs to consider those parameters
that are critical for the use on a construction site. This includes transferring the AM
technology to an appropriate scale as well as considering the different tolerances that
might occur. On-site, accuracy is measured in centimetres, not microns.[18]
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AM Envelope
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Figure 35
Visualisation of Contour Crafting set-up for the production of housing. Imagery courtesy of B. Khoshnevis.
§ 2.2.4.2
D-Shape
The production principle behind D-Shape is to scale 3DP and Inkjet methods to a
new dimension. An inorganic binder is used to bond sand and stone powder of all
sorts. Analogue to powder bed processes (SLS, DMLS), parts not joined to the building
volume during the process serve as support structures.
Large scale process chambers are achieved by using light-weight scaffolding, which,
in the future shall allow fabrication in the open. Geometric restrictions of the system
depend on the limitations of the scaffolding geometry. The dimension of the process
chamber can be as large as 6000 x 6000 x 6000 mm, but principally it can be extended
to any conceivable size.
D-Shape is another method offering the dimensions and possibilities necessary
for printed building technology. It was conceived to create life-size sculptures and
buildings, and is called ‘mega scale free-form printer of buildings’.
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AM technologies for façade construction
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To date, only sculptures and sample building parts have been realised, rework is
intensive, and no results in terms of actual material properties are available yet.[19]
§ 2.3 Summary AM technologies
The introduction of the different methods illustrates that the performance of AM
façade components can be reduced to the material properties, and is not mainly
influenced by the AM technologies themselves. All technologies have advantages
and disadvantages, but their fundamental functionality is similar. Therefore, the
initial decision to be made in terms of a possible application in the façade is to decide
whether one wants to use only proven materials – in this case metals -, or if one is open
to use yet to be developed plastics, specifically designed for a particular purpose.
The differences between the different AM materials groups are:
• the need to process metal powders in a protective atmosphere in order to avoid
exothermally reactions and uncontrolled deflagration, when coming in contact with
oxygen.
• the dependency on exclusively available materials from the system suppliers, in
order to guarantee a certain component quality and secure warranty claim for the
AM system. Only a few DMF systems allow the use of industry standard powder
without loosing the warranty claim.
• the limitation of the building chamber for the AM technologies for plastics.
‘Powder feed DMF processes’ are the best choice when trying to extend the size
of the process chamber because it allows for a combination with robot arms
or large process platforms. For plastics, only 3DP methods offer the possibility
of significantly larger process chambers. The AM technologies for ‘Large scale
structures’ obviously offer the least limited building size.
In general, the following can be summarised:
• since the systems are very expensive they need to produce high quality parts in
order to be economically efficient. The parts must feature obvious advantages over
conventionally produced parts.
• to guarantee a successful use as manufacturing methods in real-life applications,
production management, quality management and a reliable standardisation of
norms and parameters must be established.
• in addition, testing methods need to be established that evaluate parts whose
geometry changes constantly. For building products, for example, the slightest
change in the product geometry makes it necessary to request a new approval. As
such, this is not practical for AM methods since it is the uncomplicated handling
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AM Envelope
i
of changing geometries that make up the strength and justification of these
methods. If tests and certificates were needed for each part (analogue to an
“individual approval” for not yet introduced building products), this would result in
an unlimited cost explosion and therefore most likely lead to an exclusion of these
methods as ‘standard’ fabrication methods. It is more probable that the approval of
specific methods rates the resulting products as approved. The products’ properties
can then be verified with according quality management.
[15] [14]
For a further differentiation of the various available AM systems, an overview of the
most common technologies is followed by an evaluation matrix with regard to the
possible application for façade construction.
59
AM technologies for façade construction
i
List of relevant methods:
AM process (Abbreviation)
System description /
Manufacturer
Build chamber
in mm
Basic
material
Direct Metal Laser Sintering (DMLS)
EOSINT M 270 / EOS
250x250x215
Metal
Laser Engineered Net Shaping (LENS)
LENS 850-R / Optomec
900x1500x900
Metal
Electron Beam Melting (EBM)
A1, A2 / Arcam
300x200x350
Metal
LaserCusing
M3 linear / Concept Laser
300x350x300
Metal
Selective Laser Melting (SLM)
SLM 280 HL / SLM Solutions 280x280x350
Metal
AM 250 / Renishaw
250x250x300
Metal
SLM 250 / Realizer
250x250x300
Metal
DM250 / 3D Systems
250x250x300
Metal
Direct Metal Deposition (DMD)
66R / POM Group
3.2m x 3.665m
x 360˚ (robot
arm)
Metal
Electron Beam Free Form Fabrication (EBF³)
/ Direct Manufacturing (DM)
VX4 / Sciaky
4978x2286x1778 Metal
Direct laser additive manufacturing (CLAD)
EasyClad Magic / Irepa Laser 1500x800x800
Metal
Aerosol Jet System (M3D)
Aerosol Jet Lab System /
Optomec
370x470x mm
Plastics,
Metal
Selective Laser Sintering (SLS)
EOSINT P 730 / EOS
700x380x580
Plastics
sPro 230 / 3D Systems
550x550x750
Plastics
InkJet
Connex500 / Objet
500x400x200
Plastics
ProJet5000 / 3D Systems
550x393x300
Plastics
VX4000 / Voxeljet
4000 x 2000 x
1000
Plastics,
Casting
Sand
Stereolithography (SLA)
iPro 9000 SLA Center / 3D
Systems
650x750x550
Plastics
Mammoth / Materialise
2100x700x800
Plastics
Digital Light Processing (DLP)
Perfactory Xede / Envisiontec
457x304x508
Plastics
3D Printing (3DP)
Zprinter 650 / Z Corporation 254x381x203
Plastics
Fused Deposition Modeling (FDM)
Fortus 900mc / Stratasys
914x610x910
Plastics
D-Shape
D-Shape by Enrico Dini
6000x6000x6000
Mineral
powder
Contour Crafting ( CC)
Beta-System by Behrokh
Khoshnevis
6000x6000x6000
Reinforced
Concrete
Table 1
Overview of the described AM processes with abbreviation, system denomination, size of the building chamber
and main material groups.
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Evaluation matrix I: Technological comparison of methods
+++
+
11
+
+
+
4
2
processes for AM
Envelopes
++
o
Summary
+
+
use of free form
+
o
feasibility
++
o
customisation
+
materials suitable for
façades
DMLS
LENS
Ranking
Potential for AM Envelopes
enhancement of façade
technology
Potential for
fits into conventional
façade manufacturing
Application for façade
manufacturing
suitable for integrated
parts
AM Process
DMLS (Metals)
EBM
o
o
+
o
_
+
_
2
LaserCusing
+
++
+
+
+
+++
+
10
2
LaserCusing (Metals)
SLM
+
++
+
+
++
+++
+
11
1
SLM (Metals)
DMD
_
+
+
o
+
+
+
5
EBF³
_
o
+
o
+
+
+
4
CLAD
_
+
+
o
+
+
+
5
M3D
o
_
_
o
_
+
_
1
+
+
o
+
+
+++
+
8
3
SLS (with PEEK, specialized materials)
PolyJet
SLS
++
o
+
++
o
++
o
7
3
PolyJet (Material issues)
MultiJet
+
_
_
+
o
++
o
4
Voxeljet
o
o
o
+
o
+++
o
4
SLA
o
__
_
+
o
+
o
2
DLP
+
___
_
+
o
+
o
3
3DP
o
___
_
+
o
+++
o
4
FDM
+
o
o
+
o
o
o
2
D-Shape
_
___
o
_
_
___
_
3
CC
_
___
+
_
_
_
+
2
Table 2
Matrix I: potential of AM processes regarding different aspects of manufacturing with AM, and the AM processes themselves.
Upon consideration and evaluation of the entire spectrum of technologies in the
matrix shown above, the selection for the façade can be narrowed down to five AM
technologies:
• PolyJet the most visionary technology in terms of freedom of design but also in
terms of an extensive combination of existing materials all the way to composite
parts. However, it must be noted that the PolyJet technology is only of limited
61
AM technologies for façade construction
i
•
•
•
•
suitability for a direct application in the façade. According to matrix 1, the PolyJet
technology is ranked third.
Selective Laser Sintering (SLS), because the technological developments that the
company EOS conducted has made it into the market leader in the field of laser
sintering. And considering that the materials for this method are developed in
direct collaboration with the supply industry. It can therefore be assumed that
application specific materials, for example for the façade, can easily be developed.
Currently, PEEK, a high performance plastic, is the material of choice; it features
a number of positive material properties, but costs a multiple of conventional
polyamide. According to matrix 1, SLS is also ranked third.
Direct Metal Laser Sintering (DMLS) is a further development of SLS for the material
group ‘metal’. Technologically, it equals the system technology for plastics, and
is therefore principally suited for an application in the façade technology. The
processes for metal are slightly more complicated because the materials are harder
to handle. However, the components already stand up to the currently known
industrial metal parts and thus benefit from the fact that their performance is
estimable for the façade application. Therefore, DMLS is ranked second.
LaserCusing offers the material and process related advantages mentioned under
DMLS, but exhibits additional ‘features’ that make it easier to integrate the
technology into a production chain. The parts are placed in the system directly
with standard clamping systems. Therefore, the parts can be accurately reworked
with other CNC systems that use the same clamping mechanism. Like DMLS,
LaserCusing is ranked second.
Selective Laser Melting (SLM) is currently the most suitable technology to generate
metal façade components as indicated in the matrix. The system offers the
possibility to use industry standard powders and therefore economic production,
independent from specific material suppliers. The technology was not developed
from existing system technologies for plastics, but rather directly oriented toward
metal parts fabrication. In the AM industry, the developers of SLM systems have
the most experience with the material aluminium. They introduced an aluminiumready system to the market when merely producing aluminium parts was still
questioned by most experts. Standardised quality control within the system yields
tested parts; the first step toward true AM production. In addition, the developments
over the last years suggest that SLM can be quickly adapted to new fields of
application. Selective Laser Melting is ranked first in the matrix of AM technologies.
By assessing those five AM technologies again with adjusted criteria toward AM
Envelopes, a final selection of three relevant technologies can be made. DMLS was
ranked third place, LaserCusing second, and SLM first. The result of this second
assessment shows a clear dedication of this research toward AM technologies for
metals. Even though a high potential can be seen for the PolyJet technologie, still
the aspects that are more relevant for the building envelope rule over those possible
developments.
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RecomRanking Matrix II
mendation
AM processes
for AM Envelope
+
+
+
+
++
+
11
3
DMLS
++
+
+++
+
++
++
14
2
LaserCusing
1
SLM
Ranking
new materials
Summary
change of
­engineering
LaserCusing
Architectural design
Change of shape /
form
DMLS
façade
systems
potential for system
integration
evolution in
size of building
chamber
AM processes
from Matrix I
Application makes
sense!
Evaluation matrix II:
Estimate of the potential of suitable methods related to an AM Envelope
SLM
+++
+
+++
+
++
++
16
SLS
+
o
o
+
++
o
6
PolyJet
-
+++
-
+++
+++
-
9
Table 3
Matrix II: further assessment of the potential of AM on the background of Matrix I
Quantifier
Intention
_
negative
+
positive
o
neutral
Table 4
Explanation for the used quantification in
Matrix I and Matrix II
During the research it became clear that size of the building chamber and building
speed are other issues with AM, even if this fact is denied by most of the system
providers.
Meetings at FKM Sintertechnik GmbH, the largest service provider in Selective Laser
Sintering in Europe provided in-depth knowledge. Over the last years, the company
opened up their portfolio to include DMF processes, although their core business lies
in AM in plastics. This fact shows that the market has an increasing demand for DMF
processes, and that the ‘big players’ are starting to adjust to it.
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The meetings with FKM Sintertechnik provided deep insight into the development
process of AM systems. It can be stated that - over the last three years alone - all three
mentioned selection criteria for AM technologies (in this case DMF) were drastically
enhanced:
• material choices evolved from “provider-only-materials” to a selection of industrial
standard powders;
• until the end of 2012, the envelope size will assumingly increase by a factor of eight
from 250x250x250mm to 500x500x500mm;
• processing speed will be increased using different strategies: enlarging the energy
source (laser power), using multiple lasers and scanning devices (‘multi beam’).
The investigated DMF-systems all offer a different range of possible products. Some
are specifically enhanced for medical applications, others aim at Rapid Tooling. It is
always the demand for a particular application that pushes the technologies onward.
Therefore, there is hope that façade applications will drive the AM systems toward
fulfilling their specific requirements. But ultimately it is the user who needs to push the
limits according to his/her demands. It is therefore necessary to provide a thorough
description of the technologies and the possibilities and limitations involved to give the
individual user the opportunity to give it a try.[14]
In general, the following can be summarised:
• Since the systems are very expensive they need to produce high quality parts in
order to be economically efficient. The parts must feature obvious advantages over
conventionally produced parts.
• To guarantee a successful use as manufacturing methods in real-life applications,
production management, quality management and a reliable standardisation of
norms and parameters must be established.
• In addition, testing methods need to be established that evaluate parts whose
geometry changes constantly. For building products, for example, the slightest
change in the product geometry makes it necessary to request a new approval. As
such, this is not practical for AM methods since it is the uncomplicated handling
of changing geometries that make up the strength and justification of these
methods. If tests and certificates were needed for each part (analogue to an
“individual approval” for not yet introduced building products), this would result in
an unlimited cost explosion and therefore most likely lead to an exclusion of these
methods as ‘standard’ fabrication methods. It is more probable that the approval of
specific methods rates the resulting products as approved. The products’ properties
can then be verified with according quality management.
• At the moment, none of the described AM technologies offers an appropriate
building speed that would be needed to fulfil the demands of a bigger parts
production.
[15] [14]
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The intended integration into existing production technology must be considered in
order to make a final decision for or against a particular method, and the parameters
to create the component must be determined. It is not possible to make a generalised
statement that is valid for all applications alike.
The prototypes for this research were made with plastics as well as DMF methods.
Followed by a detailed examination and continued application conducted with the
DMF methods using aluminium.
§ 2.4 AM materials
A wide choice of materials is available for the AM technologies.
All manufacturers continuously develop new materials for specific applications,
because with AM, the material is the key factor for new applications. In principle we
can differentiate between ‘plastics’ (§ 2.4.1), ‘metals’ (§ 2.4.2) and ‘other materials’
(§ 2.4.3).
When developing materials for AM processes, the process requirements (melting
temperature, grain size, flowability) and the type of desired components play an
important role. 3DP models, for example, are used for design studies related to
colouring, shape and ergonomics. With these applications, there are no initial
requirements for certain functionalities or durability, but colour depth and surface
texture are critical. This means that there are different demands posed on the material
for prototypes and design samples than for those of end use parts. Since, originally, the
methods and materials were developed for Rapid Prototyping and not for end use parts,
it is necessary to focus the development of additive methods and materials on this
demand (see [3] [7]).
If used to produce consumables, all of the materials currently in use must still prove
their durability for the entire lifetime of the finished product. Aspects related to lifetime
durability are UV resistance and humidity resistance. When manufacturing prototypes
for sampling or development, the material properties might not play a key role, but
when transferring the development to the AM process they become the deciding factors
for or against the use of the technology. The big challenge for process developers is to
match the material properties necessary for a trouble free manufacturing process with
the desired properties of the final product. However, during the past few years several
methods have been ‘reconfigured’ for use with industry standards, and process-safe
materials were developed that feature the desired properties. The use of industry
standards leads to drastically reduced AM manufacturing cost, because there is no
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need for expensive specialty materials. One example is the SLM method (DMF), which
can be operated as an open system with the possibility to use industry standard metal
powder. The price for a system specific mix and an industry standard powder can
vary by a factor of ten. However, if industry powders are used with systems that have
not been approved for these materials by the manufacturers - as is the case with SLS
systems by EOS, for example - the supplier cannot guarantee any material properties
and the user looses the right to warranty claims.
The primary goal of all material developments for AM systems is to closely match the
material properties and characteristics of conventional end use parts manufacturing
processes (see [7] [3]). However, additional possibilities for AM products also come
from printed textures, material gradients, programmed porosity and others. Changing
the performance properties can therefore create new unique features from the raw
material, independent of the factually achieved material characteristics. Enhanced
product properties can be developed from a combination of functional construction
and the materials available. Such new properties can create a clear distinction
between new AM products and conventionally manufactured mass products; a direct
comparison with accepted mass products is not possible.
The methods for direct fabrication of metal parts (DMF) have undergone a somewhat
simpler development, regarding the materials used. Related to the functional construction
of building parts for the façade, a large number of established alloys and material powders
is available that stand up to a comparison with conventionally processed metal. The
modifications necessary to use these powders in AM systems are similar to those for
traditional methods. Therefore, the material properties of DMF products can be relatively
easily compared to those of metals from conventional fabrication.
§ 2.4.1 Plastics
Because additive methods were initially used for prototype manufacturing, plastics is
the largest group of materials used. Many of the products on the market are based on
proprietary recipes and compositions. Currently, all classifications and descriptions
of AM materials derive from long established materials used with conventional
production methods. The properties are developed by balancing AM manufacturability
and the properties desired by the user. All descriptions draw comparisons to industry
standards; for example for ABS the AM material is described as ‘ABS-like’, which
implicates that similar properties to those of the industry product in question are
achieved. But it is still difficult to draw a direct comparison with pure plastics. To
achieve broad acceptance of the technology as a production method, AM materials
must be comparable to conventional materials.
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At this time, plastics used in conventional production cannot be replaced by AM
materials. Instead the user needs to choose a material that comes closest to his/
her requirements. Thus, some properties can be achieved, others cannot. Permanent
resistance against humidity, ultraviolet light, heat and isotropic material properties are
problematic issues, independent of the orientation of the part in the process chamber.
And it is difficult to match the strength of die cast parts. Due to their technical
characteristics, AM processes inevitably lead to different results as conventional
methods, and therefore to different material and product properties.
Currently, plastics such as ABS, acrylate, photopolymer, polyamide (nylon), epoxy,
polycarbonate and PMMA (acryl glass) are used for these processes. Material mixes
are modified for defined applications, for example for aeronautical engineering, in
order to impart specific properties on the materials, which are later introduced to the
general AM market. Polyamide, for example, was modified in a way that it was classified
as ‘incombustible’ and could therefore be used for aeroplanes. In certain cases,
high performance plastics from conventional fabrication are made available for AM
methods. PEEK, for example, a material which was produced for special applications in
the automotive industry for the SLS method. The benefits of such a high performance
plastic materials also open up new possibilities for applications in façade and building
technology in terms of material use, component optimisation and component
properties. PEEK in particular is characterised by a number of specific benefits; amongst
others, the manufacturer points out the following properties for ‘EOS PEEK HP3’:
• high-temperature behaviour;
• high wear resistance;
• chemical resistance;
• optimum reaction to fire, smoke and toxicity;
• good hydrolysis resistance;
• potential biocompatibility;
• sterilisability.
“Due to this extraordinary combination of properties, EOS PEEK HP3 is optimally suited
for the highest requirements, for example in the medical industry and aeronautics as
well as motor sports.
For medical applications, these properties turn the material into an ideal alternative for
stainless steel and titanium. And in aeronautics and motor sports, where light weight
and fire resistance are critical, EOS PEEK HP3 has evolved to a suitable replacement
material.”[20]
It is thus conceivable to employ products made of such high performance plastics in
suitable areas of the façade if improved performance justifies the application, and if
fabrication with any other than AM is not feasible.
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Basic Material
AM process
Manufacturer
Note
ABS
FDM
Stratasys
also: ABS composites
DLP
Envisiontec
Plastics
SLS
EOS, 3D Systems
ABS-like materials
InkJet
Objet
ABS-like materials
Acrylate
SLA
3D Systems
thermoplastic materials
DLP
Envisiontec
Hearing aids
InkJet
Objet
specific acrylic mixtures
Photopolymer
SLA
3D Systems
thermoplastic materials
InkJet
Objet
jetted photopolymer
InkJet
3D Systems
thermoplastic materials
Polyamide
SLS
EOS
pure plastics
SLS
EOS
also: Alumide (Polyamide
-aluminium composite)
Epoxy resins
SLA
3D Systems
DLP
Envisiontec
also: epoxy composite
PVC-Foil
LOM
Solidimension
Polypropylene
SLA
3D Systems
thermoplastic materials
DLP
Envisiontec
Polystyrene
SLS
EOS
Polycarbonate
FDM
Stratasys
also: PC-ABS composites
SLS
EOS, 3D Systems
only for casting cores
PMMA
InkJet
Voxeljet
PMMA ~ acrylic-glass;
only applied as binder for
the sintering process!
SLS
3D Systems
PMMA ~ acrylic-glass;
only applied as binder for
the sintering process!
Table 5
The basic materials in plastics for AM, and the suitable AM process to use them.
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§ 2.4.2 Metals
Similarly to processes using plastics, special material mixes are offered to manufacture
metal parts with Direct Metal Fabrication (DMF). Only a few methods use pure metals;
in most cases specific alloys are used. Currently available materials for DMF are
titanium, aluminium, cobalt chromate, tool steel, stainless steel and various alloys of
these materials.
Flow characteristic, granulation, filling density are the determining factors when
choosing a powder for a certain method. These parameters can also have a significant
influence on the material properties of the manufactured part.
Depending on the method used, parts fabricated with DMF might need to be reworked.
Analogue to conventional metal processing methods, different material properties
can be achieved with hardening and annealing. Currently, various research facilities
examine the microstructure of the “printed” metals to enable early intervention,
possibly already during the building process. Such specialised metallurgic research
is necessary, in particular if the methods are used to fabricate components for
aeronautics but also for future façade and building technology applications.
Material mixes of plastic granulate with metal are offered for some processes that
use materials in powder form, for example ‘Alumide’ for LS by EOS. However, the
materials made with these processes are considered plastics, since plastic is the major
component. They do not exhibit the properties of a metal material.
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Basic Material
AM process
Manufacturer
Note
Titanium
DMLS
EOS
LENS
Optomec
EBM
Arcam
Titanium alloys
SLS
EOS
LaserCusing
Concept Laser
LENS
Optomec
EBM
Arcam
Aluminium
SLS
EOS
Alumide: PolyamideAluminum composite
LaserCusing
Concept Laser
DMLS
EOS
Steel
EBM
Arcam
SLS
LaserCusing
Concept Laser
Stainless steel
SLS
LaserCusing
Concept Laser
LENS
Optomec
DMD
POM / Trumpf
Tool steel
LENS
Optomec
DMD
POM / Trumpf
SLS
3D Systems
for infiltration of green
parts
Nickel alloys
DMLS
EOS
LaserCusing
Concept Laser
Bronze alloys
SLS
3D Systems
for infiltration of green
parts
LaserCusing
Concept Laser
SLS
EOS
within plastic compound
Cobalt-Chrome alloys
SLS
EOS
LaserCusing
Concept Laser
EBM
Arcam
Copper
LENS
Optomec
M3D
Optomec
Aerosol Jet System
Iron-Copper alloys
LaserCusing
Concept Laser
Metals
Table 6
The basic materials in metals for AM, and the suitable AM process to use them.
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§ 2.4.3 Other materials
In addition to plastics, other materials such as starch, ceramic, silicium, wax, gypsum,
moulding sand or electronic conducts are used for certain applications. They are often
used as an intermediate step of conventional production, for example for the very first
models for castings.
In the future, we might expect the use of other materials for Additive Fabrication such
as glass (see § 4.2.2 Direct Glass Fabrication) or wood. In order to employ the method
in the building technology the material spectrum must be broadened, and properties
such as transparency, formability and durability must be examined.
Basic Material
AM process
Manufacturer
Note
Starch
3DP
Z-Corporation
Ceramics
SLS
Phenix Systems
France
DLP
Envisiontec
3DP
Z-Corporation
InkJet
TNO
Beta system; paste
materials
Silica
M3D
Optomec
Aerosol Jet System
Wax
InkJet
Solidscape
DLP
Envisiontec
casting cores for jewellery
Gypsum
3DP
Z-Corporation
Casting sand
SLS
EOS
Resin coated sand
3DP
Z-Corporation
InkJet
Voxeljet
Conductive tracks
M3D
Optomec
Aerosol Jet System
InkJet
TNO
Beta system; paste
materials
Other materials Table 7
The basic other materials for AM, and the suitable AM process to use them.
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§ 2.5 AM evolution from new impulses
Impulses from independent fields or strong economic demands are needed to further
develop the AM technologies for new areas of application. Since there are only a
few industry segments that currently provide a market for Additive Fabrication, we
cannot expect self-motivated development for the building industry. But we can still
formulate the specifications for system technologies or materials by preconceiving
the requirements that a building technology with generatively fabricated components
would pose. These requirements can focus on specific areas of Additive Fabrication.
The most important areas are:
•
AM system technology (§ 2.5.1)
–– Process chamber
–– Process speed
•
AM materials (§ 2.5.2)
–– New materials
–– Functional gradient materials
–– Transferring AM materials to architecture
•
Automated building technology (§ 2.5.3)
–– Building robots
–– Digital fabrication
A new approach to the modified materials as well as joints and constructions for
AM gives a new meaning to the development of functional components. If the new
techniques are used intelligently, generative fabricated products can even gain
added value. For example: available lightweight building structures allow for flexible
components with improved or adapted properties and reduced material consumption.
Conversely, system suppliers must react to the findings and demands from such
new areas of application to further spread the use of AM technologies. Often,
developers lack the specific knowledge or particular way of thinking without which the
requirements cannot be detected. The following sections describe the requirements
of such technology changes in AM, and provide insight into possible applications in
building technology.
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§ 2.5.1 AM system technology
§ 2.5.1.1
Size of the building chamber
At first glance, the obvious discrepancy between building technology and AM is the
relatively small size of the process chambers offered by the systems currently available.
At the time this research work was started in 2007, an average AM system could
produce a building volume of 0.0225 m³. This relates to a process chamber with a
footprint of 30cm x 30cm and a height in Z direction of 25cm. During a period of only
four years, these boundaries were extended by a factor of 356; with current building
volumes of 8m³!
This development is used to exemplarily illustrate the dependency between technology
development and market demand: The 8m³ system is manufactured by Voxeljet in
Friedberg, Germany; the target market is the automotive industry, with its demand for
metal casting cores. The reason for this rapid development in size is the demand for
larger casting cores to be fabricated according to the ‘3D Printing’ principle. AM makes
it possible to digitally develop improved components without the need to pre-consider
whether or how they can be realised. The performance that these components exhibit
exceeds that of conventional casting cores. And since the number of items sold (in this
case large scale engines) is comparatively small, individual fabrication not only makes
sense but almost seams the only practical solution. It was always a customer demand
that caused the company to change their system. The example of the Voxeljet system
shows that contrary to the opinion of other ‘3D Printing’ companies it is not technically
impossible to increase the size of the system, even if it is true that some material and
technology parameters cannot simply be scaled up.[14] But the example also shows that
process development in other directions, for example for other target groups, does not
lie in the interest of the firms. In practical terms, the company is opposed to transferring
the Voxeljet principle to other areas than that of manufacturing casting cores4.
4
One-on-one interview between the author and a company representative of Voxeljet on 01. Dec. 2011 on the
occasion of EuroMold 2011.
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Systems with larger than average process chambers existed even before the
development of the Voxeljet machine. All of these developments were driven by
customer requests as well. The Belgium company Materialise built its first “Mammoth”
SLA system as early as in the year 2000. For a long time, this system with a process
chamber of 2.1x0.7x 0.8m, was the one able to produce the largest possible
components.[21] The development was motivated by the dimensions of dashboards
in the automotive industry. The requirement was to produce the prototypes for these
dashboards without joints.
Figure 36
Schematic presentation of the increased process chamber dimensions since 2008.
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§ 2.5.1.2
Process speed
Similarly to future process chamber dimensions, it is difficult to foresee future
developments in the area of increasing the process speed. It is obvious however; that
we need specified, realistic process speeds in order to integrate AM methods into
industrial manufacturing. Even today, the addendum ‘rapid’ is a relative term because
the methods cannot yet achieve fast processing times.
At the beginning of the development, the focus lay on comparing conventional
prototyping with Rapid Prototyping. The fact that AM technologies do not require tools
led to an advantage, particularly in terms of the time needed to turn the initial idea
into the finished prototype. Another benefit of Additive Fabrication is the fact, that the
product can be developed quickly in collaboration with the customer or user, and that
initial improvements can be integrated during the developmental stage. Since making
new tools is extremely expensive, this option simply does not exist with conventional
methods. Another advantage is that product series with a batch size of 1 are entirely
possible. This means that with AM the production of small series or even single pieces is
economical. This is exactly the strong point of Additive Fabrication: With this production
method it is irrelevant whether 100 equal or 100 unique parts need to be manufactured.
AM allows for customised products fulfilling customer demands – meaning one of a kind
products without added cost, one of a kind products at the price of mass products
(see [3]), whereby the actual time to produce these items plays only a minor role.
But if we draw a direct comparison between AM methods and conventional fabrication
methods, this advantage is lost and the processing time turns into a disadvantage.
High speed milling and CNC controlled processing centres feature disparately higher
yields because the products are generated from semi-finished parts. With Additive
Fabrication, the manufacturing cycle for each part is the same. Depending on the
method, the production time needed can usually be calculated from the building
volume. Currently, only the production of large quantities of small parts yields
satisfactory results.
For building technology that means that in order to realise large building volumes, a
large number of building parts must be available in a relatively short period of time.
Hereby, an integration of AM might interrupt conventional processes. A curved façade,
for example, designed to be produced with AM nodes, would require several hundred
nodes. It might take 24 hours to produce one component; at a high risk of defects.
This means that in order to apply AM to building technology, these processes must
be included in planning, i.e. the methods must be very dependable to ensure reliable
planning. On the other hand, the example given also shows that in façade technology
AM will not be applied to create large surfaces and volumes but rather to provide better
solutions for neuralgic interfaces and joints – areas where a different technology can
improve the whole.
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In terms of system technologies, there is a noticeable competition between different
system suppliers to offer the fastest feasible processing speeds, and therefore
an attempt to assimilate the different systems. The methods using a laser as the
light source, for example, are optimised for greater speeds by changing the energy
performance of the laser, by adding more lasers in one system, by improvements in
mirror and scanning technologies, or by changing the process chamber temperatures
and material properties. The systems also feature different resolutions which can
influence processing times. If parts are produced at higher speeds, the surfaces of the
part will exhibit lower resolution. Another options is to differentiate between contour
and filling geometry, and thus to apply different densities to different areas of a part;
which in turn will lead to time savings. To do this, two different lasers with different
light performance are used.
Another approach is the invention of systems without a laser as the energy source. By
not using a laser, the above described combination of process speed and resolution is
decoupled. One strategy is to use a masking system to expose the building material
with light. In this case the whole building chamber surface is exposed in one step; all
areas not to be solidified are masked by individual masks for each layer of the build job.
One system being investigated in is called ‘Selective Mask Sintering’, another is the
‘High Speed Sintering’. Both are aiming at new solutions to enhance building speed.
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§ 2.5.2 AM materials
§ 2.5.2.1
Functionally Graded Materials
Functionally Graded Materials (FGM) are materials consisting of different material
types that interpenetrate one another in a controlled gradient. The advantage of FGM’s
is the combination of different material properties in a single part. Gradients from hard
to soft or rigid to flexible can be printed; thus potentially replacing parts that consist of
two types of material (for example a rubber seal around a window).
A notable development in this field was conducted by the group ‘Additive
Manufacturing’ of the department ‘High Tech Systems and Materials’ at the Dutch
research institute TNO: ‘High Viscous Material Ink Jetting’.
Hereby, a software application breaks down the shape of the three-dimensional
model into layers made up of individual droplets. The number and arrangement of
the necessary droplets for each geometrical shape is recalculated and saved as a GIFF
file (Graphics Interchange File Format). In addition, the group succeeded in allocating
material properties to the required GIFF files so that one volume can consist of areas
of different materials. And these areas can feature different resolutions of the material
particles used. The system then reads the information contained in the file and
processes it accurately. The principle is based on that of Inkjetting, which sprays viscous
plastic droplets onto a building platform at high speed. With the TNO system, the
individual material droplets are directed by means of electrical power. Thus, different
materials can be melted together to form a true gradient. The material used for this
technology is a powder-filled polymer paste. The paste can contain any type of powder.
The prototype system makes it possible to print a small spiral of material with a density
of 100 per cent on one end and zero per cent at the other.[22]
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Figure 37
Prototyp of FGM part produced with the
High Viscous Inkjetting system of TNO
a
Figure 38
Beta system for High Viscous Inkjetting of TNO
b
c
Figure 39
a.) Homogenous material;, b.) joined material; c.) Functionally Graded Material (FGM)
In addition to creating gradients, the system can also print vertical ‘walls’ only a few
droplets wide – without support material and without the inherent viscosity of the
material causing the ‘wall’ to be instable. TNO sees the future of this technology in
micro printing; but it certainly offers potential for future application in AM.
Thus, AM not only allows for freedom of form but freedom of material as well. If a
system allows us to generate different materials and material compounds and to
arrange them freely, anything can be printed. However, this path breaking technology
has not yet reached marketability.
Issues to be solved relate to the software, to extending the hardware and to a controlled
placement of different materials for the different application principles of the AM
methods (see [3] [23]).
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One of the problems is that none of the CAD software programs currently on the
market can handle graded materials. In order to use FGM, new CAD software must be
developed!
In order to fully define 3D parts, a new method is needed to describe all points in
a three-dimensional space. This could be done with ‘Volumetric Pixels’ (so called
‘voxels’, see appendix A II / Glossary / Voxel). Dissolving the three-dimensional shape
into image points which can then be described with material properties.
The main reason for reducing geometric shapes to basic information such as edges
and corners is the extremely large storage capacity required. 3D models with complex
geometries would generate infinitely large datasets when described with voxels. It is
not yet possible to handle such datasets because of the limitations of the computer
processors currently available as well as the file format used to describe 3D models, the
‘*.stl’ format. Current discussion about a new, encompassing data format shows that
further development of the AM methods is closely linked to established formats and
standards (see appendix A II / Software).
But as a general material principle, FGMs open new ways of designing structures and
parts. The opportunities are connected to future visions of building construction, as
existing solutions can be thought in a absolutely new way. So far, graded materials have
been successfully produced with the LENS method.[3] Two types of titanium alloys
are printed into one another in a smooth transition. But it has to be admitted, that the
properties of those two metal alloys are fairly close to each other and do not push the
limits of the FGM capacities.
§ 2.5.2.2
Digital materials
The PolyJet Matrix technology by Objet (§ 2.2.1.5) introduced the so-called ‘digital
materials’ for AM methods: from two source materials, new, digitally specified
material mixes can be generated directly on the building platform in a multitude of
gradations. The viscous polymer droplets used for this method are deposited from two
cartridges, and mixed on the building platform according to the percentage ratio that
was predetermined in the digital model. Depositing the different materials droplet by
droplet ensures that, when hitting the building platform, the base materials mix at the
predefined ratio. The ‘digital materials’ do not yet represent ‘voxels’; but gradations
between two different materials can be approximately displayed. Such gradations are
known from handles with hard as well as soft parts, for example, or remote controls
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with a hard casing but soft buttons. This is of great advantage for realistic prototype
production (for example for flexible joints, rubber soles, springs a. o.).
Until 2012, the systems supported up to six pre-programmed material mixes made up
of two base materials each. Further development depends on improving the software,
not the system technology.
Manufacturability of ‘digital materials’ marks a significant step in material and system
development, and opens up a development of true seamless graded materials (FGM’s)
on the basis of an available AM process.
The possibility to apply freely programmable materials would be of great advantage
for various building structural details: if ‘digital materials’ were available in
certified quality for building applications, technical principles should and must
be completely revaluated and rethought in terms of design and performance. This
means that combined with known biomimicry principles, component walls could
be produced analogue to the human bone structure. Foreseeable benefits relate to
resource-conserving material use as well as to building in earthquake-prone areas
by ‘programming’ flexibility into certain components. True gradations of material
properties in an integrated component shed new light on articulated joints and fittings
of all sorts. Changes in manufacturing, assembly and maintenance expenditure shift
the range of cost and application for all hitherto known areas of use – in furniture
construction as well as in building technology.
§ 2.5.2.3
Programmed lightweight building structures
Software developers and research institutes work on developing programmed
lightweight building structures. These are controlled by algorithms and, using a
simple ‘Drag and Drop’ user interface, allow translating three-dimensional bodies
into structures with predefined properties. One product available in the market is
‘Selective Space Structures’ (by Fruth Innovative Technologien GmbH). With this
product, grid structures can be easily created following predetermined patterns. On the
computer, areas of three-dimensional geometries can be ‘filled’ with diamond-shaped,
hexagonal, triangular or other structures.[24]
In addition, a classification was developed at ‘Fraunhofer IWM’ (Institute for Mechanics
of Materials), that adapts the cell structure depending on the force distribution within
a part. Thus, following a finite element analysis, a part can be specified and optimised
in terms of the force distribution which, in turn can lead to a more efficient use of
resources. In this case, lightweight structures can be upvalued by improving the
material distribution.
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The British company ‘Within’ has brought a software application to market that
combines all aspects: lightweight structuring, FE Analysis and optimisation cycles.
This application makes it possible to develop parts focused on the intended function;
without any further limitation caused by interface issues and software limitations.[25]
Using such programmed lightweight building structures can improve the active control
of supporting structures. If the lightweight building structures are linked to the algorithm
of the machine software which controls the distribution of the supporting structure for a
technical realisation of the AM process, then the necessary supporting structures can be
integrated in better AM constructions. The geometries of metal parts can be optimised
to avoid the need for supporting structures entirely by selecting certain orientations
within the process chamber and modelling the form. This means that the quality can be
influenced ahead of time; the form is designed according to AM requirements, and time
expenditure to remove unnecessary supporting structures is eliminated.
Lightweight construction can also be functionally ‘reversed’ and thus used to form
flexible areas within a part. This means that no secondary flexible material needs to be
introduced (which, with conventional structures is the only means to create flexibility).
A structural added value is created by accumulating different performances that can be
modelled from one single material.
§ 2.5.2.4
Smart Materials
The use of the so-called ‘smart materials’ in combination with AM technologies can
mean even more added value for functional constructions. But it also means another
demand on system technology and materials.
Smart materials are materials that when combined with each other exhibit more
functionality than the individual source materials. Such materials have reversible
changing properties and react to influences such as light, temperature, and electric
fields. They can change shape, colour, viscosity, and other properties.
With glass for example, the changeable behaviour is achieved by coating. The material
senses signals from the environment (sensory function: light, dark) and reacts
(actuatory function: more or less light-transmissive). The material’s reaction is not
based on a conscious decision as the materials are not truly intelligent, but they react
intelligently by reflex when certain changes occur. Necessary controllers and energy
supplies can be mounted independently from the material – it acts as sensor and
actuator. If these controllers are teachable we talk about ‘adaptive materials’ (see [26]).
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Shape memory alloys and phase change materials also belong to the group of ‘smart
materials’. In architecture, they can be used to realise applications such as self-acting
kinetic façades that automatically create shading when the temperature changes or
guidance systems that change colour or pattern if the ambient temperature changes
and thus become visible in case of fire.
Integrating smart materials into functional constructions by means of AM methods
further increases the performance of the resulting parts. It is also conceivable to use
DMF methods to produce bimetals with integrated actuators, for example for façade
structures, i.e. they can be realised in a single part without additional assembly. In
combination with according software tools, individually set temperature ranges for
bimetals can result in individualised location-dependent solutions.
Similar to the realisation of FGM’s, the material setup of smart materials poses
different requirements on material distribution, material mix and material change
within the part, and therefore new demands on the system technology and the
programmability of such parts.
Figure 40
Smart material used in toddlers’ spoon to indicate too hot served food by colour change at the tip.
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§ 2.5.2.5
Transferring AM materials to building technology
Only a few of the materials developed for AM technologies are perfectly suited to
be transferred to architecture. Therefore the available materials need to be further
developed.
Over the last few years architecture and interior design have seen a trend toward
employing new materials. For interior design, this does not prove very difficult because
usually there are no requirements related to weather resistance, humidity resistance,
or the capability to endure permanent loads. It is therefore easier for this industry
to be open to new materials. In architecture, building technical as well as security
requirements often prevent a transfer of materials from other applications. For
planners this means that the scope of tested and approved materials is limited.
But the hesitation is also due to the fact that building components are not subjected
to regular revisions which results in a greater risk of unnoticed failure than in other
industries. There is no established technical inspection agency for façades, meaning
that the façade needs to function correctly for at least 30 years without major
maintenance. This is different for components in other industries: Besides regular
maintenance at the garage, the roadworthiness of a motor vehicle is tested periodically;
the wheels of high speed trains are exchanged after a certain kilometric performance,
and aeroplanes are completely overhauled after a specified number of hours of
operation – none of which is done in the building industry! Thus, we can, of course,
demand ‘braver’ initiatives; but these can only be based on reliable control measures so
that they can be thoroughly tested by means of real projects.
All considerations related to applying AM methods to façade technology and
architecture in general must involve further development of the materials currently
available, according to the named criteria. Both sides need to approach the issue
simultaneously: planners must be familiar with the new technologies, and the new
technologies must meet the requirements of new applications.
There is a noticeable discrepancy when considering a direct transfer of the
manufacturing principles. Current process chambers are dimensioned for components,
not for entire building elements. The system technology is filigree and the results are
therefore fine and precise. Material-specific issues must be considered if the know-how
of these systems is transferred to large-scale equipment to manufacture building parts
or housing (§ 2.2.4.1 Contour Crafting).
To transfer AM to façade technology we must not only consider the material properties
of the final product but also a change in system technology caused by the different size
of the components.
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Hereby, the main criteria are:
• Material viscosity. The challenge of manufacturing larger structures is to ensure
high quality. Problematic areas are the hardening behaviour as well as the stability
of the structure during production. Processing self-compacting concrete, for
example, poses a logistical challenge in terms of controlling the material flow at
the construction site, i.e. eliminating sintered skins between the individual layers
of different batches of material. Similarly, when using AM materials, care must be
taken to have sufficient material available, and that the base material is formulated
such that the individual layers can bond to one another yet cure quickly so that they
become one monolithic form.
• Method of application. Technologies using extrusion nozzles designed for the
millimetre range do not necessarily function as well when employed for larger sizes.
Material properties change significantly from being applied in a thin capillary tube
to a large diameter tube. Thus, changing material properties must be examined in
terms of controllability and homogeneity of the printed structure. Minimum and
maximum achievable resolution for large structure details must also be observed. It
is critical to choose the appropriate material for large areas or small details (cement,
aggregate, grain size, material mix). In general, the larger the extruded material
quantity, the lower the resolution.
• Material behaviour of composite parts. Different melting temperatures, curing
behaviour and curing times need to be considered when using different materials
in one component. If there is a universal ‘building printer’ these criteria must be
considered for each component when generating 3D data. Process temperatures
and process speeds can vary as well, depending on the chosen materials.
Appropriate software solutions for simulating deformation and tension during and
after a building job are necessary to achieve consistent material quality.
(see [27] [3])
If all these factors are incorporated into the development of new materials, such
materials are necessarily very specialised. The end use of the desired products
determines the development of the various material groups. A development for
direct application in the building technology does not yet exist. Currently, only the
Contour Crafting method and the methods for direct fabrication of metal parts employ
materials in raw material form (see § 2.2).
Functional gradient materials (FGM’s) and metals offer the most potential for direct
application in the building industry. Conceivable products could include electric lines,
products with different material densities or hard as well as flexible areas, and the
use of different materials in one manufacturing process. In order to achieve this, the
material properties as well as the manufacturing systems must be further developed.
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§ 2.5.3 Automated building construction
When talking about an AM Envelope we automatically think of large structures that
cannot be realised with the methods introduced here. It is not sufficient to simply scale
available AM methods to the dimensions necessary for a building. This step requires
several other considerations in terms of equipment technology as well as material
selection.
Still, several concepts following this approach have been developed; and the following
describes technologies that might be a step toward a ‘printed’ façade. They provide
answers to how current AM technologies can be modified to meet the demands of large
structures.
§ 2.5.3.1
Building construction robots
Based on good experiences with manufacturing robots in the Japanese automotive
industry, research and development of robotics for use in the building sector was
started in the late Seventies of the previous century (see [28]). We can differentiate
between two types of robots: systems that handle entire process steps of the building
construction (for example to create the shell construction), or robots for smaller
specialised tasks such as welding steel carriers or assembling dry walls.
In 1983, the first robot designed for flameproof coating of steel components was
presented to the public. And from 1991 until 1993, the first system that built an entire
building was realised by Shimizu Corp. in the city of Nagoya, Japan.
Figure 41
Robot system ‘T-Up-System’ by
Taisei Corp.
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Figure 42
Concrete robot by Takenake Corp.
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The invented robotic systems are linked to a fix scaffold. High-rise buildings are
constructed in layers, just like the models created with AM methods. There are two
basic systems: either each story is manufactured on the ground and moved underneath
the previously assembled stories (for example: Arrow-Up-System, Fujita Corporation),
or a ‘climbing’ system stacks individual stories on top of one another (for example:
SMART-System, Shimizu Corporation).
The initial goal of building robots was to increase the productivity and reduce the cost
for high-rise building projects. These goals were not realised because the systems
were too inflexible, and because high-rise building projects are unique in appearance
and material choice. The main benefit of automation, as it is used by the automotive
industry for repetitive process steps, for example, does not apply to building technology.
Therefore none of the above mentioned systems are in use today. The technical
problems lie in a time-intensive reconfiguration after one building segment has been
completed as well as in the large space required in the vicinity of the construction site.
And the change in appearance of high-rises today, from Euclidian forms to more freeform shapes is another reason for the discontinuation of the application.
However, one benefit that did result from applying these technologies in combination
with pre-manufactured elements was a reduction of on-site material waste of 70
percent compared to traditional building methods.
Figure 43
Welding robot, Takenake Corp.
Even though these systems are no longer in use; parts of their developments lead in a
direction that could prove interesting when combined with additive methods
(see [29] [3]).
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§ 2.5.3.2
Digital Fabrication
The Faculty of Architecture at the Swiss Federal Institute of Technology Zurich (ETHZ)
examines how modified production methods influence and retroact on architecture.
It employs an industrial robotic system to create building components. Hereby, the
research projects of Fabio Gramazio and Matthias Kohler follow different directions:
one tests the possible use of robots for digitally controlled production of building parts,
and the other examines the programmability of parts and the resulting level of freedom.
This entails a discussion of the changed design and production methods in architecture
and the influence additive methods have on construction, form and function. The
department of ‚Architecture and Digital Fabrication‘ uses a research facility with an
industry robot arm (Type: KR 150 by KuKa Roboter GmbH) for both basic approaches.
Because the robot can be used for different fields of application, the approach includes
additive as well as subtractive methods. It is the goal of the people responsible to
“examine the impact new design and manufacturing methods have on architecture
and the building industry”.[30] This encompasses a large spectrum of modern
manufacturing methods.
a
b
c
Figure 44
Test facility @ ETHZ: a.) the range of the robot arm on the rails; b.) the tool to handle the brick; c.) the application of the glue to the
brick. Imagery courtesy of Gramazio-Kohler, Switzerland.
The robotic system is used for defined projects: Brick wall elements were premanufactured for an exhibition booth and an addition to a vineyard building. Criteria
such as load-bearing capacity, implanted information (ornament), reproducibility and
programmability for digitalised production of wall elements were tested and applied
in the projects. As a result, the traditional product portfolio could be complemented
with a programmable and therefore reproducible level of freedom of form. The
offset arrangement of the bricks alone significantly changed the appearance and the
information content of the building components.
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a
b
c
Figure 45
a.) Digital idea for the wall element with ‘grapes in a basket’; b.) project application: materialising the idea with bricks into
prefabricated wall elements; c.) the final façade design. Imagery courtesy of Gramazio-Kohler and Ralph Feiner, Switzerland.
Against the background of the other additive methods, this ‘Digital Fabrication’ is path
breaking for the development of realisable printed façade components.[30]
It is a transfer of digital information to components, under consideration of the
interface issue CAD-CAM and the added aspect ‘construction site’.
All of the technologies shown in this section can be considered first steps in the
direction of ‘printed’ façades:
•
•
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the japanese robotic systems are no longer in use; however, they have the potential
to stimulate a new impulse when combined with other building construction
methods or AM technologies. One possible combination is Contour Crafting,
combining industrial techniques (crane runways) with AM technologies.
The Digital Fabrication leads toward a new way of planning and realizing
architectural ideas with digital tools. In this respect, AM technologies can offer new
solutions in transferring digital ideas to physical reality.
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§ 2.6 Summary chapter two
§ 2.6.1 AM Envelope?
The knowledge of the possibilities and limitations of the AM technology is essential for
further development, particularly as it relates to applications for the building envelope.
The benefits that, at first glance, make the use of these technologies seem sensible,
such as lightweight construction, free form, material savings and integral functionality,
vitiate traditional design strategies and thought models. They lead to radically new
interpretations of existing systems, components, details and design approaches.
In addition, consistent realisation of AM designs annihilates the separation between
primary and secondary structure. This highlights the fact that the development leads
away from the clearly defined building component ‘façade’ toward an integrated
functional zone, the ‘dynamic building envelope’. It is the integration of the new design
and production tools into the planning and realisation process that will determine
whether or not the AM Envelope will become reality.
The fact that AM is particularly suited for the realisation of new façade ideas is
supported by the nature of today’s best (façade) architecture: Realisation always
involves very small production runs (see § 4.4.3 Batch size one), and is set apart from
the standard (see § 4.3.4 Mass Customization) by the demand for individualised
building components. The fact that most buildings are very unique is usually a request
from the customer, and it is this uniqueness why virtually every building is a prototype.
Additive Fabrication is a suitable manufacturing method for such one-off solutions
because it fulfils exactly these aspects. When a façade builder has familiarised him or
herself with one of the AM methods, individualised solutions can be realised that are
sure to fit in an existing façade system. Therefore, AM is suitable as an enhancement of
known façade production methods.
§ 2.6.2 Changing the production methods
It is apparent that current production methods will change with the application of
CAD and AM Technologies. But in order to accommodate such changes, our way of
thinking needs to change as well. Developers and engineers are used to follow ‘Design
for Production’ to identify solutions. But the new technologies offer a new approach
of product development in the ‘Design for Function’.[31] This new design will unite
all of the available design and production techniques under one roof. Architects
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will have the opportunity to use digital design as a means to re-participate in the
production processes. The architect does no longer merely design but participates
in the realisation process again – like the historic master-builder - but now as the
“Information Master Builder” [32]. The architect becomes developer and data
manager for functional components. Competent knowledge of the possibilities with
which ideas can be realised brings with it greater freedom for the actual realisation. A
first intermediate step on the path to this scenario will be to compile an appropriate
multi-disciplinary planning group. It should include the expert planners necessary
to master the increasingly complex details and realisation that come with increased
freedom of geometry. Close collaboration is needed when trying to realise such ‘liquid
designs’, i.e. the perpetuated designs in free form, blob und morph. “This type of
building design dictates a very close collaboration between the participating designing,
engineering and production [disciplines]. More than ever one could speak about ‘High
Collaborative’ engineering and production.”[33]
The original goal to employ AM technologies for more cost efficient and faster
production has been replaced by the added value that they offer in terms of freedom
of form. Amongst other aspects, this could include improved component properties
or individual design. If building parts are manufactured with AM, they might offer an
added value that would justify the use of methods.
It remains to be seen what added value AM technologies can bring to the building
envelope. As described in chapter 3, the development of AM for the façade industry
will consist of several steps. It is important to change the technologies along with the
development of new applications (see § 2.5).
For the most part, the AM systems available today derive from the initial Rapid
Prototyping developments; meaning that the original purpose and motivation behind
the conception of the systems was never meant for ‘real’ production. Therefore, there
are still restrictions and limitations that need to be improved upon to achieve the
capability of serial production.
The restrictions lie in the material properties of the available AM process materials, the
realisable surface quality (as compared to the quality standards for example of die cast
components), accuracy and resolution and therefore detail fidelity and dimensional
accuracy after the CAD file has been transferred into the AM process, and consistent
reproducibility with fixed quality standards (see appendix A I / Standardization).
In spite of these limitations, Additive Fabrication offers great potential to
fundamentally change building technology.
The conceptual ideas introduced in § 4.1 show that applications that promise added
value can be conceived and planned even before the technologies are actually available.
Metals are an interesting group of materials when considering a realistic application
of the AM methods to the façade technology: Since their material properties are
well known, metals are easy to evaluate and assess by planners and manufacturers.
Materials are already used for many technical solutions in the building industry and
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thus complement existing systems and constructions when used with AM. It is to be
expected that they will be accepted for new applications because the handling of and
the trust in the second oldest building material in history has grown over a long time.
However, when seeking to employ direct fabrication of metal parts (see § 2.2), one has
to be aware that DMF methods still involve more complex manufacturing process than
the methods for manufacturing plastic products.
Metal as base material for additive processes is still a specialised field, and a
combination with plastics is not possible due to process limitations. The great freedom
of form and construction that AM Technologies seem to offer is still limited for complex
metal applications. Thus, functional components (articulated joints, bodies-withinbodies, etc.) cannot be formed entirely freely as is possible with plastics.
Another limitation when transferring the technologies to the building industry is
the fact that regulations or quality standards for products manufactured with AM
technologies have not yet been established. A catalogue of traceable criteria must
be developed so that products can be compared to each other and to conventional
mass products. A rating system for the manufactured parts, quality standards for the
available methods and materials as well as quality control for the individual methods
are key requirements when developing a mutually accepted manufacturing method
(see [7]).
System manufacturers have been working on this issue over the last few years.
Increasingly, quality management systems are integrated in the manufacturing
equipment; the production steps for each job are documented; thus making the
process steps, i.e. malfunctions, traceable. This aspect is critical when manufacturing
ready-to-use products because the products are sold under warranty. The company
EOS calls this process ‘Part Property Management (PPM)’, established to ensure
the standardisation and comparability of building processes and building results.
Specifiable building parameters can be used to achieve reliable component properties
across different systems.[34]
The fact that the development of using AM for ready-to-use parts is fast progressing,
infers quick improvements, because AM itself is a development that was not
foreseeable 20 years ago. And even if Additive Manufacturing is developing in markets
other than the building market, the general requirements and conditions remain
the same.
A good example to highlight the fast-paced development of AM technologies by
comparing them to another technology is the development of Mass Customisation
(MC) in the building industry (see § 4.3.4): 20 years ago, it was inconceivable to
economically create glass façades that did not feature homogenous glass areas. The
development of CAD-CAM production techniques made it possible that façades with
glass panes that are completely different from one another are commonplace today.
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Equally, in retrospect the integration of AM methods into building production will
prove just as natural.
§ 2.6.3 Challenges
The challenges of further developing AM for façade technology can be categorised in
‘material’, ‘technology’ and ‘production’:
•
•
•
Material:
–– the physical properties of AM products: they need to mimic generally accepted
mass products;
–– the materials used under consideration of cost, properties, reworkability and
standardisation;
–– accuracy of the fabricated products in terms of product properties such as
surface finish and dimensional accuracy;
–– programming and fabrication of Functionally Graded Materials (FGM).
Technology:
–– the possibility of exact reproducibility of identical parts across different
production batches and with different yet technically identical equipment;
–– producible product size: in macro as well as micro range;
–– process speed;
–– achieved resolution with largest possible form, smallest printable detail.
Production:
–– software access for the user: intuitive processing of 3D data;
–– cost efficiency compared to conventional building products;
–– lower manufacturing cost with AM (equipment cost, maintenance,
material cost).
Besides explanations about the development and functionality of the AM technologies,
this chapter also established an understanding of the technical basics for future
scientific considerations to apply them in façade technology. It became apparent
that the AM technologies have evolved from a specialised branch for prototyping to
a legitimate production method. Promising technologies for a transfer into façade
technology were listed. Limitations in system technology that still exist today can
be easily eliminated in the near future, i.e. the system suppliers will solve issues
concerning component size, process speed and material choice for the Additive
Fabrication.
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References chapter 2
[1]
Wohlers, T., Wohlers Report 2008, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2008: Fort Collins, Colorado, USA.
[2]
Grenda, E.P. Castle Islands Worldwide Guide to Rapid Prototyping. [cited April 2012]; Available from: http://
www.additive3d.com/home.htm.
[3]
Hopkinson, N., R.J.M. Hague, and P.M. Dickens, Rapid Manufacturing. An Industrial Revolution for the Digital
Age. 2006, Chichister, England: John Wiley and Sons, Ltd.
[4]
Neef, A., K. Burmeister, and S. Krempl, Vom Personal Computer zum Personal Fabricator. 2005, Hamburg:
Murmann Verlag.
[5]
Grenda, E. Castle Island`s worldwide guide to rapid prototyping. [cited April 2012].
[6]
VDI, VDI 3404 Generative Fertigungsverfahren Rapid-Technologien (Rapid Prototyping) - Grundlagen, Begriffe,
[7]
Wohlers, T., Wohlers Report 2007, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Qualitätskenngrößen, Liefervereinbarungen, V.D. Ingenieure, Editor. 2009, Beuth Verlag: Berlin.
Progress Report. 2007: Fort Collins, Colorado, USA.
[8]
Bullis, K. GE and EADS to Print Parts for Airplanes. [cited May 2011]; technology review newsletter].
[9]
Lenz, J. Konturnahe Kühlung durch direkten Aufbau der Formen, EOS GmbH, Deutschland. in Rapid Tech 2008.
2008. Erfurt.
[10]
Bonne, R. (2012) Gehäuse-Fertigung im Additive Manufacturing Verfahren. developmentscout - online-portal
for industrial R&D.
[11]
ASTM, Typologies for layered fabrication processes, in ASTM F2792, A. USA, Editor. 2009, ASTM International
Committee F42 on Additive Manufacturing Technologies: Annual Book of ASTM Standards, Volume 10.04
[12]
Burns, M. fabbers.com. 1999 -2003 [cited April 2012]; Available from: http://www.ennex.com/%7Efabbers/.
[13]
Gershenfeld, N., FAB - the coming revolution on your desktop - from personal computers to personal fabrication.
2005, Camebridge, MA, USA: Basic Books.
[14]
Strauss, H., Personal Communication with suppliers and adopters of the technologies on various meetings,
conferences and fairs., t. Author, Editor. 2011: various.
[15]
Woodcock, J., Additive Manufacturing in metals in tct magazin. 2011.
[16]
Hopkinson, N., Anchorless Selective Laser Melting, in tct Live. 2011, tct Magazin: Birmingham, UK.
[17]
Trumpf GmbH, DMD-Verfahren, http://www.trumpf.com/scripts/redirect2.php?domain=http://www.trumpflaser.com/&nr=207&content=207.presse7327.html. [cited April 2008].
[18]
Khoshnevis, B. Contour Crafting. 2006; Available from: http://www.contourcrafting.org/.
[19]
Dini, E. D-Shape. 2009; Available from: http://d-shape.com.
[20]
EOS. Materialdatenblatt EOS PEEK HP3. 2010 [cited April 2012].
[21]
Materialise. Materialise - innovators you can count on. [cited May 2012]; Available from: http://www.
materialise.com/mammoth-stereolithography.
[22]
TNO NL, High Viscous Material Inkjet Printer, http://www.tno.nl/content.cfm?context=markten&content=case
&laag1=181&item_id=413. [cited May 2008].
[23]
Chua, e.a., Database and Data Communication Network Systems - Techniques and Applications, ed. C.T.
Leondes. Vol. Volume 2. 2002, San Diego, California: Elsvier Science (USA).
[24]
FIT. pro-fit.de. 2012 [cited 2012; Available from: http://www.pro-fit.de/welcome.php.
[25]
Within. within-lab.com. [cited April 2012]; Available from: http://www.withinlab.com/.
[26]
Müller, G., Intelligente Materialien. Fraunhofer Magazin, 2003: p. 30-31.
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[27]
Soar, R. Loughborough University, England; freeform construction; http://www.freeformconstruction.co.uk/.
[cited April 2008].
[28]
The International Association for Automation and Robotics in Construction, iaarc.org, http://www.iaarc.org/
frame/quick.htm. [cited June 2008].
[29]
Cousineau, L. and N. Miura, Construction Robots, The Search for New Building Technology in Japan. 1998: ASCE
Press.
[30]
Digitale Fabrikation, ETH Zürich, Architektur, Forschung, http://www.dfab.arch.ethz.
ch/?lang=d&loc=AF&this_page=forschung&this_id=78. [cited May 2008].
[31]
David L. Burell, M.C.L., David W. Rosen, Roadmap for Additive Manufacturing - Identifying the Future of
Freeform Processing, M.C.L. David L. Burell, David W. Rosen, Editor. 2009, University of Austin, Texas: Austin,
TX, USA. p. 92.
[32]
Kolarevic, B., Architectur in the digital age: Design and Manufacturing. 2003, New York: Spoon Press.
[33]
Eekhout, M., Tubular Structures in Architecture. 1 ed. 2011, Geneva: CIDECT and TU Delft.
[34]
EOS. EOS Whitepaper: Part Property Management (PPM). [cited April 2012].
[35]
Wikipedia, Online Enzeklopädie, http://de.wikipedia.org/wiki/Hauptseite. [cited April 2008].
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3 Toward AM Envelopes
This chapter answers the following research questions
• Which research approaches lead to first experiences with AM technologies in the
building envelope?
• What are the effects of product-oriented project results on a general transfer of the
AM technologies to façade technology?
• What means of assistance for planners and users of AM must be generated in order
to guarantee AM oriented application in the façade?
In this chapter the core of the research work is introduced. The goal of the conducted
investigations was a product-oriented research of details based on a post-beam façade,
and the transfer of the findings to façade technology. The results are described by
means of AM optimised components that can be achieved when applying AM to façade
technology.
The description chronologically leads through the developments from small façade
details to a complex façade component.
A summary of the optimisation results rounds off the chapter. It offers an intermediate
result to evaluate the potential of AM for the building envelope.
§ 3.1 Building envelope requirements
Since approximately 20,000 years human beings create housing for cultic as well as
living purposes. In short, our built environment as we know it today has developed
from those origins in small increments. Analogically, building technical details evolved
– from questions that arose and solutions that the relevant craft permitted. Openings
were built into structures as access routes, for lighting and ventilation, and for the
desire of the user to create comfortable living quarters. They developed from simple
openings to covered frame constructions to the actual window and, at the beginning of
the 20th century, to the façade as a clearly separated component of the building.
[1] [2] [3]
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Figure 46
Façade development.
Developments always involved specialisation / fine-tuning: Simple drapes in front
of wall openings evolved into operable windows; the curtain wall façade with single
glazing casement windows evolved into the post-beam system, later element façades;
the mere building enclosure turned into the vision of a building skin with all of the
necessary functions that allow for a comfortable and energy efficient building, and as
intermediate steps to a true skin the double façade, then the decentralised HVAC units
and, still unsolved, the ‘Polyvalent Wall’ by Mike Davies.[1]
Each era had its own technological revolutions: Due to the development of the
steam engine the handsaw evolved into a chainsaw, the smoothing plane into a
planning machine – which made it possible to realise true to dimension parts and
thus functional operable window sashes; the drawing board turned into a CAAD
System (Computer Aided Architectural Design), which makes digital and networked
planning possible – in the context of architectural design we also talk of the time
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‘before grasshopper’ and the time ‘after grasshopper’ to manifest the massive
changes in design that occurred since architects started programming (scripting);
serial production turned into the parallel ‘just-in-time’ production that, through
configuration, permits individual serial parts. And with this development came the
desire to enable a seamless ‘file-to-factory’ process that allows to create manufactured
structures from digital designs without interface losses on a 1:1 scale – and this is
where we are today; new technologies push the boundaries of the feasible. With the aid
of the production facilities available, digital designs can be realised up to approximately
90 per cent, accruing future technologies close the gap of the remaining approximately
ten per cent, which includes Additive Manufacturing.
With AM technologies, functionally designed components can be realised that hold
improved joints and material-optimised mechanisms. Of course, the initial goal is
not to replace established and proven façade systems and to understand AM as the
magic bullet with which our façades – and in a secondary step our buildings – are ‘3D
printed’ from now on out. Still, now is the time to begin improving upon the critical
points and improvable details of façade constructions by employing the available
new technologies – to which AM belongs. We will not be able to print entire profile
geometries of a post-beam façade but the connection pieces for complicated joints
of different roof pitches. With AM, such nodal points can be designed in different
forms than hitherto known solutions, and allows for optimised solutions with fewer
parts, less material and improved assembly; resulting in less labour. To directly ‘print’
entire façade structures with all functional connections can only be considered in a
subsequent step.
It is essential to emphasise the importance of the building envelope as a neuralgic
interface to the different requirements of the building [1]:
•
•
•
•
•
•
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climate;
load transfer;
comfort;
technology and assembly;
performance;
appearance.
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Figure 47
Façade functions
AM can improve the building envelope, and it can fulfil the demand for ‘dynamic
building envelopes’. The actual realisation of these improvements is closely linked
to the developmental steps of the AM technology (see § 2.5). It depends on how
intensely all participants discuss the potential of AM for the building envelope. The
goals and visions specified pertain to all functional areas of the building envelope:
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Optimisation of the room climate:
• by changing the geometry of the envelope depending on the ‘load case sun’;
• by integrating better building services (channelling, placement, more user-friendly
control panels, amongst others);
• by reducing heat loss, i.e. optimising insulating properties;
• by improving passive energy management, i.e. energy gain, avoiding losses.
Optimisation of structural aspects:
by reducing self-weight;
by supporting a load adaptive load-bearing structure (wind, earthquake);
by distributing material according to an optimised force path;
by the reduction of self-weight in lightweight structures.
•
•
•
•
Comfort optimisation:
• with ergonomically designed components;
• by increasing the functional integration for the user (control panels, remote-free
operation via voice control);
• with intuitive building services and automated activation (climate, system
technology);
• with improved adaptation to individual circumstances, for example light directing,
view, orientation of the openings;
• with a design-optimised appearance: ‘true’ representation of a free form (visual
comfort);
• with a material-optimised appearance: Blob shapes are generated with Blob
technologies, i.e. cast and injected rather than built as a post-beam system.
Façade technology:
• assembly optimisation with ‘digital pre-fitting’ and simulation;
• assembly optimisation with more detailed planning, i.e. improved because more
detailed execution planning and early control in the file,
• assembly optimisation with functional connections;
• assembly optimisation by reducing the need for adjustment at the construction site,
i.e. increased system security;
• assembly optimisation with integrated component identification (AM RFID, AM
barcode, AM QR code).
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§ 3.2 Research approaches
Individualisation, technology transfer, absolute freedom of form: These are the
keywords that define the challenges as well as the charm of printed building
envelopes. Which challenges in façade technology do we face in the new millennium?
What demands will the user have on the future façade? If we are looking for an allencompassing answer to these questions, AM alone certainly cannot provide the
solution. But it can be part of it. This mind set, a curiosity about anything new, and
possible technology transfers to other disciplines are the factors that generated the
demand for an AM Envelope. How can we enter this new world while maintaining
a practical orientation? How can we break up existing structures while remaining
anchored in the planning task at hand? In this dissertation the path to answer these
questions is based on product-oriented research. It shows the relevance of the topic in
light of a commercial company. The result is connected to the restraints of the market
and the demand for improvement – or even innovation. Completing the contract
research must be followed by returning to be open for the more global aspects and
broader horizons. Led by the goal not to actually print our buildings but to exploit AM
to control the neuralgic interfaces and important areas of our buildings - technically
secure and using the latest technology. Additive Manufacturing is one means to
success – and a very fascinating one at that.
Figure 48
Consistent AM design
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Considering the ever more creative designs for high-rise building projects, we must
question the consistency of their realisation and the way the user interacts with them.
At first glance, the most obvious applications for the new technologies derive from
issues with known, advanced systems rather than from a fundamentally new approach
to research their potential. This leads to the risk that developmental opportunities are
not addressed because the drive for development originates in gridlocked, conventional
structures. In order to assess innovations objectively, conventional opinions must be
abandoned and the user must be conscious of the consequences of these innovations.
If, according to contemporary taste, buildings are merely clad in a free-formed envelope
(fig. 48, to the left), does a new technology improve the connections and details (fig.
48, in the middle), or can it even lead to a new understanding of the built environment
as an integrally developed living environment (fig. 48, to the right)?
At the beginning of the research, different goals were defined as a starting point.
These visions are linked to different levels of development of the current standard
façade systems:
• semi-finished product level;
• component level;
• system level.
To limit the expectations, these categories were linked to time periods: applications
that can be realised over the next one to five years with currently available technologies
(semi-finished product level); results that seem realisable in a period of five to ten years
(component level); and lastly applications that cannot be realised with the currently
available technologies, expected in a time period of 25 to 30 years (system level). This
chronologic categorisation makes it possible to create a direct link between today’s
production and the requirements of modified designs. What begins with a simple change
in standard components will, according to the project participants, evolve into a holistic
approach – to a ‘printed’ façade, and in a broader sense to a dynamic building envelope.
Potential for optimisation and or modifications were identified by means of an analysis of
the currently available façade components for a post-beam façade under consideration
of the frequency of their application. The individual products were selected based on
how often they are used, as well as against the background of production optimisation
and, partially, in terms of their development history in the façade system (semi-finished
product level). The ultimate objective of the work was a façade node (component level)
that represents the state of the art in 2010 in the field of ‘Direct Metal Fabrication’ (DMF)
– the application of additive methods to create metal parts.
The developments in the semi-finished products and component level highlight
that AM has a strong effect on the development of new parts in building technology.
It became apparent that actually designing such parts to a satisfactory level takes
up significantly more time than expected. The component and system levels were
examined by means of written out visions and first visualisations (see § 4.1).[4]
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§ 3.3 Influence of AM on the development of façade constructions
The following describes optimised parts from the system portfolio of Kawneer-Alcoa
(façade manufacturer) that were examined during the research project. All parts are
evaluated in terms of their potential for optimisation, the result of the optimisation
attempts and their ranking after completion of the research project.
The first approach was to examine connecting elements that are rarely used. The goal of
the optimisation was based on the great potential for ‘on-demand production’; which,
with AM can be executed directly by the user. An integration of additive methods
into the façade manufacturing production cycle could eliminate cost intensive stock
keeping. Parts are produced for each order individually in the quantity required.
Various components from this part of the product portfolio were analysed and
evaluated in terms of their potential when manufacturing, stock keeping, performance
and ease of assembly are changed. This type of evaluation must include not only the
component itself but the entire process chain.
§ 3.3.1 Corner cleats
Working on the semi-finished part level means to optimise the individual product. As a
first case study, corner cleats for frames and window profiles from a current production
series were examined. Typically, these components are used to stiffen profile corners as
well as a connecting piece for gluing and grouting the profiles.
Figure 49
Principle application of corner cleats for window-frame mounting.
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Figure 50
Corner cleat gluing, @ Kolf en Molijn,
façade manufacturer, Netherlands
i
Due to the increasing number of different window profiles available, the corner cleats
also differ slightly in thickness, leg length or boring. They are created from extruded
aluminium profiles, produced with a matrix as yard goods and cut to the desired length
in the workshop.
Each article must be available at all times; the increasing number of different systems
offered by one supplier results in a large number of different parts that need to be in stock.
Figure 51
Corner cleat aluminium profiles; corner cleat cutting with circular saw, @ Kolf en
Molijn, façade manufacturer, Netherlands
Figure 52
Storage boxes for the various types of
corner cleats, @ Kolf en Molijn, façade
manufacturer, Netherlands
Ordered quantities of the extruded profiles can be better quantified in kilometres than
in metres. This in turn means that these kilometres of profiles are bound capital and
inventory until possible future use, independent of the actual demand. This problem
could be eliminated if single parts of rarely used product groups are manufactured justin-time, made possible by the AM methods.
Due to their size, corner cleats could already be manufactured with AM today. The small
dimensions make it possible that several parts could be produced simultaneously,
which in turns points toward a possible integration into façade production.
Additionally, possible improvements on the parts can increase their performance. With
the currently used method of production, the corner cleats are merely pushed into the
frame profiles where they stabilise the corners with bolts or grouting. However, the
main factor providing stability for the corners of the frame is the additional PU glue that
needs to cure for up to seven hours. During this time, the frames are subject to twisting
and shifting, i.e. they must be carefully stored during the entire curing period. If, on
the other hand, a click connector was integrated into the corner cleat, a pre-tensioned
connection with offset borings could be created that is self-clamping and torsion-free.
In addition, a larger surface would allow for more effective gluing.
The following describes three different variants of corner cleats that were subject of this
research project.
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271.xx
30
°-1
80
°
§ 3.3.1.1
w
Figure 53
Corner cleats for non-orthogonal window frames; angle manually adjustable; Imagery and illustrations from
Kawneer-Alcoa digital catalogue, Issue 10/2010
a. Potential for optimisation:
The part was used as a starting point. Optimisation potential is given by the fact that
the angle (from 30° to 180°) has to be adjusted manually. A higher degree of stiffness
of the corner connection could be achieved if the part was printed with ‘digital’ angles.
b.Result:
The angles of a window system could be digitalised and transferred to the necessary
CAD files for production. The corner cleats could then be printed individually for one
entire window or façade system, in the exact quantities needed for a particular project.
The cleats would be more rigid and stiff due to the fact that the loose pivoting joint is
eliminated.
Material savings are achieved by implementing a lightweight structure into the massive
area of the cleat.
c.Ranking:
The idea was not further developed in the project. The results were clear and the
potential for an immediate application obvious, supported by the feasible size of the
parts. The application and realisation with DMF is possible, savings can be achieved
because there is no more tied up capital for infrequently used products.
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Figure 54
Rendering of 271.xx, detail; left: standard solution digitally drawn from e-catalogue; right: AM optimized
solution; digitally reduced material and light weight structures. Digital branding on the side of the part: this could
also be used for part identification.
§ 3.3.1.2
272.xx
Figure 55
Drawing of standard corner cleat 272.xx from Alcoa
e-catalogue.
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Figure 56
Original aluminium corner cleat and a first prototype
with integrated snap-on functions and leightweight
structures (right).
i
Figure 57
Rendering of part detail: 272.xx, AM optimized solution; digitally reduced material and snap-on features for
additional fixation in the Aluminium profiles; digitally drawn from e-catalogue.
a. Potential for optimisation:
The second corner cleat was optimised in terms of advanced functionality. The frame
corners are manually mounted in the workshop. The profiles are glued and fixed
and need to rest after assembly before the corner can be subjected to stress. The
optimisation is aimed at enlarging the surface for glue adhesion and the fixation of the
corner by inventing snap-on fittings that eliminate the waiting period before the frame
can be further processed.
b.Result:
The part was optimised in shape and function. The snap-on feature works well with
plastics; it is not clear yet what modifications would be needed for DMF processes. The
geometry of the part remained the same, but by enlarging the surface for adhesion,
material savings were achieved.
c.Ranking:
A similar idea of screw-less corner cleats was invented in the 1970’s and is protected
by patents pending. Therefore this concept was not further pursued; however, it offers
potential for future investigation.
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§ 3.3.1.3
210.xx
a. Potential for optimisation:
The third approach for corner cleats was developed to test the functional
implementation in a window frame. The original part differs slightly from the previously
introduced part #272.xx. Two different kinds of cleats need to be used for the chosen
system: One for the outside, another one for the inside of the frame. Again, the snap-on
function was implemented; results and ranking are similar to #272.xx!
b. Result:
The part was optimised in shape and function. The snap-on feature works well with
plastics; it is not clear yet what modifications would be needed for DMF processes. The
geometry of the part remained the same, but by enlarging the surface for adhesion,
material savings were achieved.
c. Ranking:
A similar idea of screw-less corner cleats was invented in the 1970’s and is protected
by patents pending. Therefore this concept was not further pursued; however, it offers
potential for future investigation.
Figure 58
To the left: standard corner cleats made from aluminium profiles; to the right: AM corner cleats made from ABS plastic with the FDM
technology.
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Figure 59
To the left: standard corner cleats made from aluminium profiles; to the right: AM corner cleats made from ABS plastic with the FDM
technology.
§ 3.3.2 T-Connector
Figure 60
T-connector for orthogonal connection in AA-100 mullion and transom façade system by Alcoa; Imagery and
illustrations from Kawneer-Alcoa digital catalogue, Issue 10/2010.
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Figure 61
Standard T-connector mounted to AA-100 mock-up.
Based on the initial approach to examine the product group corner cleats, the focus
of the project lay on a T-connector of the post-beam façade AA-100. Hereby the
considerations not only included the benefits of prompt production but also the
performance characteristics within the façade system.
The optimised component therefore is an improved ‘digital’ façade joint that, in
combination with digital planning tools enables individualised façade geometries, and
offers a structurally optimised system.
A ‘digital’ connector:
The availability of additive methods adds one more link to the chain of true ‘file-tofactory’ production. In an ideal scenario, the digital planning stage would be followed
by a CAD-CAM production process; which would enable us to create parts for a freeform façade with all angles and adaptations of the same quality than those of an
orthogonal solution with standard products. In this particular case, a connecting
piece between post and beam would optimally transfer the loads via the beams into
the pillars. Orthogonal façade or not - it would ensure a force-fitted connection of the
components.
There is a standard connector for today’s post-beam systems that also works for nonorthogonal façades. However, it does not fulfil all of the requirements of a post-beam
connection, and, due to the limitation of the extruded sections, is limited in shape to a
multiple of the same geometry defined by the used matrix.
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Figure 62
To the left: standard free-form element, @ Kolf en Molijn, façade manufacturer, Netherlands;
to the right: standard free-form connector, @ Kolf en Molijn, façade manufacturer, Netherlands.
For the advanced AM part, all necessary angles and borings are digitally integrated into the
design. Therefore perfectly fitting connections can be planned and manufactured for each
nodal point of the façade. Additionally, added value is achieved through material savings
and force path optimised shapes, even for such small parts. Assembly is done analogous
to the orthogonal connection using the standard post-beam system components, all of
which can be pre-manufactured with CNC milling equipment with exact angles.
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Figure 63
3D connector: rendering (left), printed part in stainless steel (right), realized on a DMLS system by EOS @ FKM Sintertechnik GmbH
Figure 64
Digital T-connector mounted to AA-100 mock-up.
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Figure 65
FE-analysis results; conducted by Kawneer-Alcoa during the project.
Figure 66
Evolution from Standard (left), to ABS Prototyp (middle), to 3D connector in Stainless Steel (right).
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a. Potential for optimisation:
This part offers good potential for optimisation because it has different designs to
fulfil the free-form task of the AA-100 system. The digital integration of angles and the
possibility to save material and enhance performance show how the system benefits
from AM improvement.
b.Result:
Material savings of 25 per cent were achieved compared to the orthogonal standard
connector by digitally ‘cutting off’ the material where it was not needed.
The mounting system remained the same. Therefore all tools and accessories of the
standard AA-100 system can be used.
c.Ranking:
The advanced connector is the first part of the project that was ‘printed’ in stainless
steel. It shows the possibilities and the change in design and performance, even
if it lacks further engineering. The potential for AM optimisation is more obvious
with this component than with the corner cleats. Improvements in the performance
characteristics for deformed façade geometries are easy to retrace. Therefore the
connector is an important milestone in the development toward an AM Envelope; it
can be seen as the first important intermediate result (for further details and technical
drawings see appendix A I / Additional information on the research results).
However, initially the digital connector is only a very first suggestion on the way to a
true AM connector. Therefore, during the project was tested in terms of its structural
performance within a façade system.
The modified connector was digitally simulated and evaluated by means of a FE
analyse. Due to the new requirements originating from the different, non-orthogonal
component geometry, the simulation with currently available software could only be
done for a slightly modified component. The FEA analysis on the following pages shows
that a second optimisation run has to be conducted according to the results of the
numeric simulation.
The results show that, if applied to the façade, the component would fail. The material
savings at the component shoulder results in less stiffness in case of wind loads and
tensile stress. In order to avoid such deformation, a cross-tie behind the screw hole
would need to be added to enclose the shape, and thus be able to transfer occurring
loads. Several optimisation runs would have to be conducted to achieve an operational
component (see § 3.5). But a digital approximation of the component can be done
anytime. The approach of the ‘Bionic connector’ was not continued during the project.
The current state of development highlighted the most important issues, and was
further examined as part of the following project goal: the combination of post and
beam geometry in a nodal point.
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§ 3.3.3 Nodal point
§ 3.3.3.1
Nematox I
The third approach was to realise a one-off solution for a deformed post-and-beam
façade system. The result shows the development and realisation of a digitally planned
and additively manufactured façade node – the Nematox.
Figure 67
Non orthogonal façade construction, resulting in a joining detail that is inadequately solved with silicone.
The idea to construct arched façades by using a hybrid construction method of
standard sections and accessories with additive manufactured ‘3D façade nodes’ came
up as one intermediate result of the research at the University of Applied Sciences in
Detmold. In order to avoid imprecise cuts caused by free-form angles, this approach
resulted from the first optimised components described above. Sometimes free-form
angles lead to undesirable leakages due to the complicated geometries that appear in
the joints. Afterwards sealing is done by using wet silicone on the construction site.
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To enhance such a free-form façade joint, all benefits of the previously developed
‘digital connector’ were further developed and combined into one integral nodal
point. The resulting nodal point is, in terms of its dimensions, directly manufacturable
with AM. All the needed angles can be digitally implemented in the dataset by
software settings of parameters (parametric design). This digital design allows for the
optimisation of different aspects: maximum length of transoms according to loads,
minimum deformation in the joints according to glazing requirements, maximum
needed number of joints according to near net shape geometry.
By digitally merging the post and beam profile, only rectangular saw cuts are necessary
to assemble the façade. This reduces cutting scrap and facilitates assembly. In
addition, the critical issue of water transfer from the beams to the channels of the post
is defused and the system thus technically improved. Also, all accessory parts from the
existing façade system can be used, even for a deformed façade.
Digital planning and generative fabrication allow for such solutions and facilitate the
difficult situation in the workshops and on-site. While, until now, sections and cover
strips had to be manually adapted to non-orthogonal angles, the new system uses only
right-angled cuts – easy to accomplish for the contractors at both the workshop and
the construction site. The façade can be pieced together easily, because the individual
parts could be equipped with unique digital identifiers.
Due to ever increasing demands in terms of tightness and thermal transfer, the
development of sections over the past years has led to increasingly complex node
solutions. When eliminating the need to connect at node level and connecting parts
outside of this ‘critical zone’ where all seals, water ducts and fixings come together, the
potential for defects is greatly reduced. One result could be a system-fit execution of all
seals without the need to cut non-orthogonal angles on-site and add wet silicone.
Figure 68
Rendering, NEMATOX I, 3D façade node for Alcoa ‘Next’ façade system.
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Figure 69
Principle of construction for façade node within a façade system; all angles can be digitally adjusted to the
desired geometry and deformation.
With this approach a combination of applied standards and digital enhanced node solutions
was realised for today’s façade technology. By blending new ‘high tech’ parts into tested and
verified systems, advantages from both can be combined to an even better solution. By only
re-designing the critical points with AM, the needed hybrid system is invented.
A hybrid combination of the digitally catalogued parts together with smooth logistics
(On-Demand-Production) could result in optimised time management.
§ 3.3.3.2
Nematox II
The Nematox Node is the first printed façade node for a 1:1 mock-up. It represents the
state-of-the-art of AM in façade systems in 2010. Hybrid constructions from system
components and individualised AM parts show a realistic path that could be followed
as a first step.
To produce this type of node, it takes a lot of effort and understanding of both the
engineering aspects of façade systems and the great range of CAD tools to sketch and
script the node. For the two versions of the nodal point - Nematox I and, subsequently
Nematox II – 120 hours of CAD engineering were needed to generate a print-proof
*.stl-file: 60 hours were needed for the first attempt with all joints and dimensions to fit
the standard aluminium profile. This was followed by the decision to reduce the costs
for the prototype by changing the dimensions of the profiles to a smaller size. These
changes took another 50 hours of CAD work. Ten hours of computation and translating
were needed to finalise the *stl.-file, and another two hours to place the part in the
virtual building chamber of the AM system software.
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Figure 70
Rendering: NEMATOX II, 3D façade node for Alcoa ‘AA-100’ façade system.
Figure 71
Nematox II mounted to AA-100 mock-up.
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Figure 72
Nematox II mounted to AA-100 mock-up; detailed view of the aluminium part.
Figure 73
Printed nodal point in aluminium, realized on a ConceptLaser system by EOS @ FKM Sintertechnik GmbH
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Figure 74
Printed nodal point in aluminium, realized on a ConceptLaser system by EOS @ FKM Sintertechnik GmbH
And finally, it took 76.5 hours of processing time to ‘print’ the nodal point in
aluminium as a 1:1 prototype with LaserCusing (by ConceptLaser). Upon completion of
the build job, the part was finished and post-processed in another four hours of labour.
The team that designs parts like this should be just as hybrid as the façade itself! The
first idea emerged relatively quickly. After developing the t-cleat part, the next obvious
step was to virtually merge the two connected profile geometries to get a nodal point
with all needed connections. Even though this process sounds straight forward, a lot of
thinking was required to determine all relevant objectives.
The first test-drive was very valuable for all aspects of the development, and opened up
many new questions and fields of investigation.
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Figure 75
Build job preparation: screenshot of orientation of Nematox II within the DMLS building chamber representation; indicated in red is
the needed support structure; @ FKM Sintertechnik GmbH
a. Potential for optimisation (both nodal points):
The intersection of a façade system is an area with high optimisation potential in itself.
As all the different drainage, tightness and connection parts are joined in one neuralgic
spot, enhancement can be achieved for all these performing aspects. This first attempt
is one approach to an assembly-friendly system that combines standard solutions with
one-off parts.
b.Result:
The nodal points show a way to realise free-formed façades with a standard façade
system combined with parametrically planned components.
The optimisation potential stretches across different areas of façade manufacturing
and assembly:
• reduction of cutting scraps by avoiding long mitre cuts; the angular deformation of
the façade is solved with the nodes, the connections are realised with 90° cuts;
• 90° cuts also reduce the risk of inaccuracies during cutting at the construction site;
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•
•
•
•
the realisation of accurate joins is improved, and the use of later deposited
permanently elastic sealing materials is reduced;
a combination of several components in one nodal point minimises the number of
work steps and therefore assembly time and reduces the risk of using wrong parts;
a high degree of prefabrication can take place in the safe work environment of the
workshop, which in turn reduces inaccuracies and other production risks on-site;
regional manufacturing of the nodal points reduces otherwise necessary
transportation expenditures.
Double curvature glass planes will be the result of digitally planning two different
angles at the nodal points. For manufacturing, this is another challenge of the building
envelope; however, in the context of solving the nodal points for the load-bearing
structure, this issue is mentioned here, but not solved. In the case of glazing such a
façade, digitally planned and load-optimised glass carriers could offer an advantage.
It was a conscious decision not to include articulating parts within the node geometries
(adjustable connections or joints) in the development at this time. This is in connection
with the already mentioned difficulties that the necessary supporting structures pose.
Another reason not to add any further complexity to the node was the significant
data volume, because the impact on generating the print file and processing the AM
software program was unforeseeable. These functions should definitely be further
investigated in a next step.
The Nematox nodes are worked out and engineered to a certain point; but the
development should be continued to exhaust their full potential.
c.Ranking:
The task of a ‘digital’ façade node was fulfilled. The presented node is state-of-the-art
in the field of AM production in 2010, with the support of a service provider instead of
in-house technology. The presented node showed the boundaries of CAD engineering
in the project. CAD engineers are needed for further evolution in collaboration with a
façade planner.[4]
For further details and technical drawings see appendix A I / Additional information on
the research results.
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§ 3.4 Results from part optimization
Façade manufacturers offer several different window, door and façade systems. For
many projects, these systems fulfil the needs and demands of architects and investors.
But some projects require specific solutions with tailor-made products. Just-in-time
production with AM could help establish a new balance between tailor-made solutions
and system offerings.
In the research project presented here, the current limitations of the additive methods
were consciously neglected to stay open minded to all possibilities. First concrete
numbers for the production with additive methods must be generated using ‘honest’
calculations and by trying to quantify the constructive added value of improved parts.
These numbers do not yet justify broad application, but they also do not negate it.
Thus, generative methods have a development potential that reaches beyond a pure
comparison of cost per unit. If assembly and manufacturing are optimised, the basis
for the calculation changes substantially. And, with an on-going change in the markets,
the flexibility of production as well as the reduction of the self-limitation to certain
established manufacturing methods should be considered.
It was proven during the research that the large number of parts used for existing
façade systems offers great potential to apply AM for the production or evolution of
those parts. The findings can be subsumed as follows:
• generally, the parts are small and therefore meet the maximum size of current
process chambers;
• the material used is mainly aluminium and can be realised with existing DMF
processes;
• production batches can be planned in advance;
• with the existing CAD-CAM process, AM can be integrated into the production;
• most parts already exist in the digital catalogue of the manufacturer, which can be
used as database for part optimisation;
• new functions and features can be incorporated into the parts using the design
potential of AM, leading to better performance;
• further thought has to be put into the future design of and with AM. A design
guideline (see § 3.6) is needed for each specified AM system that is implemented
into the production chain.
It is foreseeable that with the growing knowledge of the possibilities of Additive
Manufacturing its use in architecture and building construction will increase.
Collaboration is essential when developing reliable solutions for future envelopes
(and incorporated future façade systems) that will satisfy both the supplier and the
architect/customer. As of today, AM solutions are not yet feasible for façades in a
broader sense; however, it is crucial to begin to develop visions so that we can adopt
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them as soon as possible. Everyone becoming aware of the fascinating possibilities that
AM offers feels the potential they bear for future applications.
The availability of AM technologies might make it possible that individualised parts can
be digitally designed and adapted in the near future. The façade industry in particular
can benefit from the fast developments of ‘Direct Metal Fabrication’; advanced parts
are then ‘printed’ as a service to clients or as an enhancement of the façade suppliers’
production. The potential of AM almost demands that each façade node is designed
individually, thus furthering the idea of true free-form architecture. The presented
results are only the first steps of implementing additive methods into the building
industry. Further examination of the possibilities will offer even more options that will
change our built environment.
First, we should try to identify possible applications between low-priced and
established mass production and individualised ‘one-off’s’. We must find strategies
for a sensible application of these technologies for different industrial areas; mere
availability does not justify their use in all cases. On the way to every-day production
with additive methods, perspectives must be identified for a step by step introduction
of the technologies into the various markets. Research projects and ongoing
examination of the possibilities are the first step; and future market demand will
contribute to solving existing technical challenges.
It is important to change the technologies along with the development of new
applications (see § 2.5). In spite of today’s limitations, additive methods offer great
potential to fundamentally change façade technology. The first optimised parts
and conceptual ideas (see § 4.1) show that AM applications promise added value
compared to traditional building methods, and that they can be conceived and planned
even without the technologies being available to the full extend, yet.
§ 3.4.1 Potential for façade application
When considering future applications of AM in the façade industry, metals will prove to
be interesting materials due to their well-known properties.
However, when seeking to employ direct fabrication of metal parts one has to be
aware that DMF methods have not yet reached the same developmental stage as the
methods for manufacturing plastic products (see § 2.2.3), and lead to a more complex
technology.
Considering the possibility of substituting metal-only solutions by introducing highend plastics into complex façade details is a crucial strategy if following the ‘AM path’.
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For the façade node described above, this would directly lead to the further
development of Nematox II. To reach the next level, testing on a larger scale is required
(1:1 scale). A life-size mock-up could be used to check the real effect of AM parts
inside a mounted façade system with its multitude of dependencies. This would
offer the opportunity to verify all necessary joints and connections. A next step would
then be a real façade project, where the different levels of AM opportunities could be
tested under real conditions (storage, manufacturing, integration into production,
just-in-time management, logistics, fit and assembly, performance during long-term
testing). Such a project would ultimately prove the feasibility of AM for façades - or
not. It would also allow a more detailed look into a possible file-to-factory process for
façade systems. And finally, all results could be combined into the requested AM design
guideline (see § 3.6).
§ 3.5 Requirements for optimizing standard parts with AM
To encompass the findings of the research, a catalogue of requirements shows the key
aspects for optimisation with AM in a condensed way.
The catalogue is divided into three parts: from the perspective as a façade system
provider or façade installer (the future producer with AM), from the perspective as
an AM user (engineer, designer or architect) and related to the parts themselves. At
first glance the last aspect might not seem conclusive, but it is important to clearly
phrase the requirements posed on the parts themselves. AM is only practical if the
manufactured part reflects the technology applied to make it: it does not make sense
to use AM to print rectangular massive blocks but rather to create AM optimised
representations of the desired function!
Façade system provider / façade builder:
• it only makes sense for a system provider to become an AM producer if the high
initial investment will pay back;
• one proper façade project might be sufficient to pay back the initial investment
(AM system);
• it does not make sense to compare mass produced mounting accessories to printed
parts – the price will always be a killer argument against an honest calculation;
• keeping the technology in-house gives the system provider a unique position in the
field of façade system providers;
• specialised one-off solutions can be realised with a wide range of contractors/customers;
• expertise can be concentrated in one place;
• limitations and potentials of the AM system will be explored exclusively by the
applying engineers.
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AM user:
• ‘plug-and-play’ is a must: the use of AM should be as easy as using a tablet
computer;
• the decision has to be made whether CAD engineering is done in-house or by an
external service provider;
• the design of parts has to follow an AM design guideline to keep the costs as low as
possible and achieve maximum extra value from the application of AM;
• better understanding of the process leads to better parts;
• combining different CAD systems to a holistic approach - numeric analysis, FEM,
thermal simulation, load bearing optimisation;
• highly specialised expertise is needed to meet the complex requirements of façade
systems;
• by following these rules the user immerses him or herself deep enough into the new
way of designing to make it everyday business.
AM parts:
• material savings are crucial;
• design for AM is crucial - surface orientation, incorporated supports, minimum height;
• free-form is limited by the process – the method of production limits the
practicality of certain shapes;
• smart use of support structures is crucial - for example ‘Selective Space Structures’,
software to generate filigree lightweight structures and to integrate them into the
production process with AM (to design parts that do not rely on supports, but are
self-supporting);
• if required, incorporate support into the design to avoid material waste and issues
with (surface) finishing during post-processing;
• extra value from better/new performance – requires further exploration and will
bring change for many aspects of the existing systems;
• scripting and automation of complex façade systems has to be accomplished - BIM,
parametrical design, adopting ‘mother’ files;
• the surface of the end-part is the only limitation – everything else can be
reinterpreted.
• Standard parts can be optimised for different aspects:
–– number of parts sold during the year vs. min. number of produced parts – stock
keeping;
–– standard parts vs. extra value – more strength, specific shapes with higher
performance, better performance with less material;
–– extra value vs. production related limitations - for example transom with nonorthogonal solutions;
–– assembly process vs. time – optimise assembly by combining parts to fewer
single parts;
–– manual labour vs. smart parts - for example implementation of snap-on
features into fittings.
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§ 3.6 The need for an AM guideline
The research results presented here highlight the necessity of a user guideline. Such a
user guideline must include different aspects of applying AM in a production chain, and
must enable different perspectives on a production with AM. On one hand this means a
technical manual, but on the other it must also be a design aid for improved AM parts.
An AM guideline should cover the following topics:
• how to judge the AM process for a particular part/production;
• how to decide for a particular AM process;
• how to start a design development;
• how to respect the needs of other specialists in the process;
• how to design a ‘mother file’;
• how to implement the necessities of a prototyping idea into a ‘AM proof file’;
• how to optimise a *.STL or *.STEP file for AM production.
The structuring of such a guideline arises from the particular processing phase of the
manufacturing process: In the case of the façade node Nematox II, it should be divided
into the steps ‘system check’ and ‘production check’ which are further described
in the following. The findings resulting from such systematic work can be used to
develop ‘design guidelines’. Such a guideline must be developed for each of the AM
technologies in order to exploit the full potential of each manufacturing method.
§ 3.6.1 System check
System check in this respect means: choosing an appropriate AM system, fitting the AM
part into the façade system.
Considering the Nematox II as the starting point, adaptations in terms of engineering
must be carried out to use the node in a façade system. The prototype is the result of an
initial development, and has not undergone an optimisation cycle. Initial optimisation
can be done directly in the CAD file:
• numerical analysis (FEA) for the performance within the façade system, related to
dead loads, wind loads, heat transmission, etc;
• additional material savings with regards to the load performance;
• shape optimisation for accessory fitting;
• virtual fit-and-assembly tests.
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The next step is to carry out a dedicated finite element analysis for the node that, over
several runs, changes the geometry and therefore the CAD file. Hereby, the profile
geometry of the connecting standard profiles as well as the angles selected for the
façade form are the only parameters that are fixed. Wind loads, dead load as well as
thermal and hygric properties can already be virtually tested.
Ideally, the CAD file is parameterised accordingly, i.e. the boundary conditions for
setting the parameters are specified in accordance to the standard parts but are also
influenced by the performance aspects (loads, span width, angle of deformation, a. o.).
In a cycle of optimisation, the changes in the CAD file, the FE analysis and the
boundary conditions result in an adaptation of or approximation to the optimum
structure and shape of the part in the CAD file, according to the required performance.
Such structural adaptation leads to modified material distribution, formation of
compression and tension zones as well as stress-less areas that are merely influenced
by the specified surface geometries.
After the file has been optimised, the most appropriate AM technology for the part in
question must be selected: due to the great variety in systems, an intensive market
research should be conducted for a first assessment. Certain demands on the desired
properties of the product further limit the choice. In all cases, it is important to
research alternative manufacturing methods as well to identify the best possible
method for the task. Hereby the main criterion is the part geometry. When selecting
production processes, there is always the possibility to achieve a better result when
combining AM with other manufacturing methods, than by using AM alone.
If elements or components need to be adapted to an existing system, their suitability for
the system must be evaluated. How high is the degree of specialisation of the desired
component and the system used? Can all system-dependent accessories be used? Does
the application of AM lead to further changes in the components or system elements?
If the development is based on an existing prototype, a realistic assessment must be
done after this initial process, and preparations must be made for further optimisation.
In this regard it is very important to select the proper inter- or multi-disciplinary team
of participants. The following specialists/consultants are needed for a satisfactory
optimisation:
• CAD experts;
• FEA experts;
• parametric designer;
• structural consultants;
• AM system providers;
• material producers;
• AM service providers;
• providers of alternative processes (for example fine casting);
• façade system providers.
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A thorough examination and discussion of this approach to product development can
aid in establishing the necessary processes.
Figure 76
Representation of file optimisation in several cycles
§ 3.6.2 Production check
Production check in this respect means: fitting the new AM parts into the production of
façade producers, optimising the AM file for the production of the part.
The shape and appearance must be checked if an AM part is to be integrated into an
existing system (design check). If the part file is modified after initial optimisation,
the geometry of the part might also change. In this case, the design and function of
the part must be discussed and possibly readapted by means of physical prototypes
and simulation (system fitting). Geometric changes might result in changes to the
fitting of accessories. This highlights the multilayered interdependencies between the
changes and results from optimisation runs. The graphics below show a simplified
representation.
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The following optimisations steps would run for further development of the Nematox
façade node:
• generate new *.stl file for the production of Nematox III;
• first prototype of Nematox III (FDM, STL);
• reassessment of desired performance;
• review with technician concerning the fitting of necessary accessories;
• re-discuss the prototype;
• conclusion of first and second optimisation;
• generate final ‘mother file’;
• identify a suitable method to produce AM parts;
• decision on material, process, shapes;
• adjust AM parts after first assembly accordingly.
Figure 77
Representation of AM part optimisation in several cycles
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§ 3.6.3 Design rules
The objective for a design guideline must be to establish target-group specific,
universally accepted statements that support the user in the decision making process
in the different areas of functional constructing. The dependencies between the
participating disciplines must be clearly visible to enable seamless decision making.
Hereby, the different interests of all of the parties involved must be considered: those of
the AM system operator as well as those of the user who wants to generate ready-to-print
files, as well as those of the customer who wants to use AM as a service provided to him.
§ 3.6.3.1
Optimization aspects
Considering the necessary progress of optimisation, there are also different points
of view that need to be taken into account: ‘engineering aspects’, ‘design aspects’,
‘system aspects’.
Similar to the different levels of a component or file optimisation, different criteria will
influence the resulting optimisation. Hereby it is important to weigh the aspects against
each other and to select the appropriate method for the particular product / project.
The decisive factor of this new manner of designing is the complexity of the areas
touched upon and the expertise involved. The difficulty will be to name one primarily
responsible “master builder”5 who consolidates the decisions and bears the final
responsibility (see [5] ).
If the different aspects are optimised together, they will have to be weighted, which
will lead to the favour of one and disfavour of another. The decision making is complex
since a great number of different parameters and criteria can be specified for each
aspect. Consideration of all aspects during optimisation requires the designer, engineer
or architect to have expert knowledge in all areas involved, or at least the ability to
properly communicate all occurring problems and necessary decisions.
5
Citation: Branko Kolarevic, „… as the opportunity for architects to reclaim the lost ground and once again
become fully engaged in the act of building (as information master-builders).“ in Reference [5] Kolarevic, B.,
Architecture in the digital age: Design and Manufacturing. 2003, New York: Spoon Press. Page 27.
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Possible engineering aspects:
• minimal wall thicknesses;
• maximum possible component size;
• orientation within the process chamber; accordingly, the changes in surface quality
and the resulting process speed;
• strategy ‘hatch – offset – contour’, weighing component density, material use,
geometric accuracy and process speed;
• reduction of notch stress by sensibly rounding out notches.
Possible design aspects:
• form and appearance of filling elements in a grid system (glass fillings: straight
surfaces, single curvature surfaces, double curvature surfaces);
• joint design and arrangement;
• appearance of the component in the system (accentuated, exposed, subsidiary,
integrated);
• surface design (quality, structure, materiality);
• formative integration of structures and geometries.
Possible system aspects:
• determining the reference lines;
• optimising cutting scraps for standard components;
• further development of sealing layers and arrangement;
• integrating the technologies into development and production;
• adjusting the connection points and joints in iterative steps.
The main objective of the guideline must be to simplify information. The user as well
as the engineer must find the necessary information to successfully apply AM to their
specific application.
Recommendations about the cost for the use of AM technologies cannot be provided
in such a guideline because they are subject of strong fluctuation and change.
The question whether AM is used as a service or an in-house process is another
fundamental process decision that influences the cost calculation.
Just as components and data sets can only be optimised with several optimisation
cycles, the guidelines must also be fine-tuned and adapted.
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Figure 78
Representation of the optimisation aspects and related areas
§ 3.7 Summary chapter three
The presented components and parts show one side of the range of results that the
project brought up. One of the most important results is the fact that the project does
not conclude the research, but rather opens up an array of questions and new starting
points for further development and future approaches toward the use of AM in building
envelopes, building construction, and architecture in general.
So all of the limitations mentioned here do not represent the end of this development
but offer the chance to conduct targeted research in those areas on the basis of the
knowledge gained here. The involved project partners did not only gain knowledge
about the currently available technologies in AM; the questions that arose would not
have been identified without this first approach.
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New input from AM but also strong hints about the limitations of the DMF processes
regarding our current standards in façade systems became apparent during the project.
To make use of the opportunities that AM generally offers, and that originally led to this
project (free-form, lightweight, material savings, integrated functions …), make current
strategies and ways of thinking obsolete and lead to a radical reinterpretation of the
existing systems, parts, details and designs of building envelopes.
“Historically, architects drew what they could build, and built what they could draw
[…]. The straight lines and circular arcs drawn on paper using straightedge and
compass have been translated into the materials made by the extrusion and rolling
machinery. This reciprocity between the means of representation and production has
not disappeared entirely in the digital age. In the realm of representation, the modeling
software based on NURBS has infinitely expanded what could be ‘drawn’, while the
digital fabrication technologies have substantially expanded what could be
manufactured and built. As a result, the geometric complexity of buildings has
increased dramatically over the past decade.”[6]
The results of this research activity can be categorised as follows: the advantages of AM
(generally, status 2012), the disadvantages of DMF (generally, status 2012), the effect
of AM in component design, and the effect on digital design with AM.
1
The advantages of AM:
• freedom of shape and form;
• lightweight constructions;
• force following shapes;
• material only where it is needed;
• manufacturing on demand;
• no tooling-related limitations during production.
2
The disadvantage of DMF:
• expensive if purchased from service providers;
• costly as investment;
• time consuming with current production speeds;
• support for overhangs and undercuts as well as heat control are required;
• any shape with an incline of less than 45° needs to be supported;
• different orientation in the process chamber leads to different surface qualities.
(This means a limitation in taking advantage of AM as stated above!)
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3
Effect on current design:
• it might be quicker not to enhance existing façade solutions for AM, but to start
engineering from scratch;
• parts and fittings of façade systems need to be reinterpreted against the
background of the given limitations of DMF (if DMF is the chosen manufacturing
method);
• example: support structures required for the DMF process need to be integrated
into the structural design of façade parts (turn a disadvantage into an advantage;
support structure turned into a lightweight internal structure of a DMF part;
• current ‘design for production’ has to be specialised to ‘design for DMF’;
• a ‘design guideline for AM in façades’ has to be developed.
4
Effect on advanced parts:
• only the geometrical ‘outside’ (surface) of the part must be specified, everything
else is open for reinterpretation;
• all components other than the surface (see aspect above) will be executed according
to the ‘Design for AM’ code;
• things will change!
This chapter described possible first steps for an integration of additive fabrication into
production, and introduced and assessed results of an application in a façade system.
Aspects are listed that are important results of the project: they open up additional
questions that can be used to pursue this research beyond the scope of this work. In
terms of façade technology, results were found in the individual components. And a
first building stone was developed for a complex façade construction. At this point is
becomes apparent that an optimisation of existing components alone will not allow
us to fully exploit the potential of the new technologies. New development originating
from the functions of a part leads to freer results, but it also requires a radically new
method of thinking by the developer.
The necessity of a design guideline for additive methods was discussed; content and
structuring were introduced. The facets of an intensive discussion about the manifold
aspects of a consistent application of AM were formulated and evaluated.
This part of the research work made it possible to observe the influences and effects
of the application of AM technologies on the production of system components.
Information to better assess the AM technologies as they relate to an AM Envelope
were gathered, and the results help in evaluating the potential of additive methods.
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References chapter 3
[1]
Knaack, K., Bilow, Auer, Façades. Principles of Construction. 2007, Basel: Birkhäuser Verlag AG.
[2]
Ulrich Knaack, M.B., Tillmann Klein, Façades. imagine 01, ed. K. Knaack, Bilow. Vol. 01. 2008, Rotterdam: 010
Publishers. 128.
[3]
Martin Meijs, U.K., Components and Connections. Principles of Construction. 2009, Basel: Birkhäuser Verlag AG.
[4]
Strauss, H., AM Façades - Influence of additive processes on the development of façade constructions. 2010,
Hochschule OWL - University of Applied Sciences: Detmold. p. 83.
[5]
Kolarevic, B., Architecture in the digital age: Design and Manufacturing. 2003, New York: Spoon Press.
[6]
Kolarevic, B., DIGITAL PRAXIS: FROM DIGITAL TO MATERIAL, smooth morphologies, http://www.erag.cz/
era21/index.asp?page_id=98 2005.
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4 Use and application of AM in façade
technology
This chapter formulates the open questions concerning a continuation of the research
results. Defined suggestions for an application in different areas of the façade are given
and evaluated. The end of the chapter describes the steps necessary to continue the
efforts to further the application of additive fabrication in the façade technology.
•
•
•
Which developments of the AM technologies for façades are conceivable?
Which façade applications can result from these developments?
What effect can an integration of high-tech technologies have on building
technology?
§ 4.1 Technological developments in the (near) future
Additive Manufacturing, as a consequence of its definition, describes the production
of ready-to-use products. But since the AM technologies available today cannot yet
deliver this capability economically and technologically, concept ideas based on the
status quo were developed. Therefore, from the point of view of the current state of
knowledge the results of this research project must be seen as ‘true’ Rapid Prototyping
approaches, even if Rapid Prototyping describes only a part of the generative methods.
They are insufficient for a long-term prognosis of the potential of the technologies.
Ultimately, all considerations lead to a ‘functional building construction’ and the
development of ‘dynamic building envelopes’.
These thoughts about the future of AM for the building envelope round off the
discussion: The development of AM is an evolution running in upward spirals that,
based on similar approaches, will lead to a new level of realisation. The developed
prototypes pioneer this evolution, even if they do not represent today’s manufacturing
reality. All of the components shown are prototypes that can only be elevated to the
next level of realisation after they have been tested in a real façade project. Only after
such real object testing can the prototype evolve into a product for (individualised)
mass production.
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For façade technology – and consequently for architecture in general – this evolution
can be executed in individual steps:
Step 1:
An AM façade detail that can be realised with currently available AM technologies.
Combined with established façade products, this AM façade detail features advantages
in terms of production, assembly and/or construction.
The planning process is similar to that of conventional manufacturing: AM parts
are optimised on the basis of existing products and are manufactured on demand.
Only one tool is added to the manufacturing process; it is one additional link in the
production chain of the façade supplier, the façade builder or the AM service supplier.
The final product ‘façade’ is the same as those created with conventional methods; the
potential for optimisation is on the part of the manufacturer, not the user.
Hereby, AM is a possible enhancement of the production.
Step 2:
A modular part that complements conventional façade technologies. The functional
added value lies in the combination of conventional façade systems with individually
fabricated AM parts. The size of the parts depends on further development of AM
systems (see § 2.5.1).
Compared to conventional manufacturing, the planning process is enhanced: the
classic approach depends on adapting the design to the tools and products available.
The solution is an approximation to the initial design, and is therefore always a
compromise.
Therefore, AM extends the process: realisation is only partially based on available
system components; certain areas of the task are reinterpreted considering the
possibilities of AM and are solved based on the desired functionality. This means
that the planning and execution part of the process chain needs to be extended to
encompass AM. For execution planning, this is a significant step because AM does
not only change the performance properties of the façade but also influences the
production process itself. The product ‘façade’ distinguishes itself from traditional
solutions with newly won freedom of form and performance. The user benefits from
advantages related to the realisation possibilities of the design ideas, and technically
improved solutions resulting from the CAD-CAM process.
AM is a possible solution approach from the series of digital tools available.
Step 3:
The AM Envelope that migrates from design to building construction in one step
There will not be any AM systems for these concepts in the near future. However,
contemplating such encompassing AM applications stimulates the continuation of the
AM development.
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Compared to conventional manufacturing, the classic planning process is abandoned:
To realise an AM Envelope, we no longer need the system solutions currently available
but a combination of all available products enhanced by AM. The planning process
is based on the desired performance of the building envelope. It materialises the
necessary parts by exploiting all available production tools. This change requires a
hybrid planning team that develops the optimum process chain for the design together
with the façade builder.
By coupling the possibilities of the AM technology with the requirements of the
building envelope, the implementation of AM into the production process can be
estimated. The development of semi-finished goods consisting of small parts to a
dynamic building envelope becomes comprehensible.
[1] [2]
To illustrate the potential of AM for the building envelope, the following lists the
expected changes of the development steps over the next 30 years.
Within the next five years: …
… AM will change existing component details. The technology will be integrated into
the production of distinguished architectural projects. It will bring the façade one step
further toward an AM Envelope.
The development of the applications over the coming years is clearly foreseeable:
In principle, all necessary technologies are available. If not certain metals, then
high performance plastics will be used as building materials in building technology.
Components will improve because engineers will examine the potentials of the
technology in greater detail. Initially, AM parts will be integrated as parts of existing
systems – improved joints, integrated components, combined functionality. AM is
available as a production method – AM is reality.
The AM services that, over the past ten years – have been established to produce
everyday items – fabbing (see § 2.2.2) – can be conceived for other areas as well. If
a company cannot afford the initial investment for an AM system, special purpose
associations can be formed to reduce the cost for the individual partner. Similar to the
development in the craft trade following the introduction of CNC machining centres
(for example CNC trimming and joining systems for carpentry). Following market
adjustment, the use of CNC technologies is now common practise; we no longer ponder
its practicality. Likewise, an increasing number of service providers will spread the
matter of course of the use of AM.[3] [4] [5]
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In five to ten years: …
… AM will have found its way into the workshops of façade builders due to improved
system technology. An intuitive approach to the technology will lead to numerous uses
as a natural part of the production process.
Considering the rapid development since their invention in the Eighties, it is to be expected
that subsequent development and consequently application will take place just as rapidly.
Dealing with 3D data comes more naturally, and therefore the understanding of the method
and quality of the necessary data related to the different manufacturing technologies and
the design. In ten years, the discussion about data formats, quality assurance and further
development of AM applications will have reached a level that will annihilate today’s
concerns about the integration of the technology. Good economic prognoses as well as
a noticeable shift in the AM market point toward increasing strength of the AM industry.
And lastly through mergers of the big players from the different AM segments to effective
corporations that consolidate the entire bandwidth of AM technologies under one roof (for
example the announced merger of Stratasys and Objet in the beginning of 2012). Such
pooling – and thus monopolisation – will influence the technological evolution as well:
larger corporations require greater revenue, i.e. ‘real’ production throughput and revenue in
number of systems. This in turn demands opening up new markets. It can be expected that
building technology will be recognised as one such market.
But new markets also mean new requirements: for example technical limitations in terms of
system size and process speed need to be overcome. In the coming years, current attempts
to establish norms and quality management will lead to a consolidation of the trust in the
performance of AM products. And therefore even the conservative building industry will
discover the technologies – with current participants becoming early adopters.[6]
In twenty five to thirty years: …
… the manufacturers of large (façade) components will use Additive Fabrication with
various materials for combinable hybrid processes, to produce dynamic building
envelopes and the according primary structures. ‘Fluid Design’ will turn into a natural
‘Cross-Over Design’, analogous to the required functions.
System technology will further develop toward hybrid manufacturing. The combination
of different disciplines is as important as the combination of different manufacturing
methods. The process of choice will depend on the product, not on the availability of
particular means of production. Production will be democratised; everybody will be
a producer, the monopoly of mass products will be replaced by a conscious choice of
individualised (and therefore intensively planned) products. In the building sector the
borders between interior and exterior space will have shifted. The dynamic building
envelope will fulfil far more functions than expected, which opens up new options for
design and use of interior spaces. The design of our built environment will be partially
parameterised; production will be based on practical automation. It is no longer relevant
whether individual spaces are designed according to the Blob or Bauhaus style – there will be
suitable manufacturing methods for both approaches. The implicitness of the functionality
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of the generated components will have changed: Energy efficiency, sustainability and
functionality are fundamental parameters of fulfilling individual needs; only the choice of
the production means and the diversity of design options will have increased.
Following efforts to question the necessity of the designer, a societal consensus was
formed that design is no longer a random product of independent algorithms but
rather an expression of targeted considerations.
The same considerations were verified by trying to generate buildings with purely
automated manufacturing methods – in addition to ‘Information Master Builders’,
today (2040) there also are ‘Digital Craftsmen’ who comprehend their work as a virtual
and analogous craft.
§ 4.2 Principles for AM Envelopes
Concept ideas were worked out into ‘principles’ to illustrate the above described
development of AM for façade construction. Some of these are closely related to an
AM Envelope, some not so close; but they all illustrate new approaches for further
development with the new technology. Therefore, all principles were subjected to an AM
ranking which differentiates between and evaluates six parameters of the idea potential:
• the time frame of a possible realisation (yesterday – tomorrow);
• a differentiation between different part sizes (micro – macro);
• the probability of realisation (Yes, we can! – can we?);
• an allocation of the part category in façade construction (detail – system);
• the type of application (interior – façade);
• the type of execution (craftsmanship – High-Tech).
Figure 79
Evaluation schematic for AM envelope principles.
The evaluation facilitates a comparison of the ideas and offers a distinct assessment of
whether the ideas are suited for AM or not.
The principles are categorised as follows: Façade applications (§ 4.2.1), the new work
material glass (§ 4.2.2) and targeted AM developments (§ 4.2.3).
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§ 4.2.1 Façade application
Energy Cavity
Imagined by: Holger Strauß
AM ranking
Description
Here, an AM product substitutes the standard cover caps and parts of the extruded façade profiles in glazed facades. A high-tech
part with integrated heat exchanger offers energy gains within an existing part of the building – the post-and-beam façade. The
advanced cover caps and profiles can be used for refurbishment projects or for partial upgrades during refurbishment. They can also
be deployed as part of a green energy concept for up-to-date buildings.
An energy generation component is implemented into the - so far unused - cavities within structural profiles in both cover caps and
post and beams. If the profiles are used for air-conditioning, no additional AC units need to be mounted on the façade, eliminating
these unsightly devices.
All required ducts and pipes are printed onto the inner walls of the profiles. Additional optimisation, such as pollen filters can also
be integrated.
The principle of a heat exchanger is used to gain heat or cold by exchanging energy between different surfaces. The efficiency
depends on the amount of surface area created. Standard heat exchangers can be created by mounting thin plates together, similar
to the radiator in a car. Extrusion methods can generate large surface areas which in turn are used to transfer the heat to the surrounding air. By using 3D printing technologies, huge additional surface areas of any shape or size could be produced to exchange
heat or cold. The method can also be applied to gain sun energy and/or to easily create heating and cooling devices.
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Solar Kinetic Bi-Metal Façade
Imagined by: Daan Rietbergen, Holger Strauß
AM ranking
Description
Functionally Gradaed Materials (FGM) made from two metals can be used to produce parts that deform at precisely predictable
rates. An accurately calculated mixture of two different metals is implemented into one single part using CAD. Changing temperatures control the behaviour of the bimetal parts, thus making the façade change accordingly. There is a broad range of possible designs: inspired by shingles, slate cladding, fish scales and many more, smaller or bigger parts of the façade could be heat-adaptive.
Application in the façade could be used for shading, ventilation or as visors.
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Wind Adaptive Façade
Imagined by: Ulrich Knaack, Phillip Meise, Marcel Bilow, Holger Strauß
AM ranking
Description
This idea features integrated piezo spring point holders inside the façade construction. When wind loads act on the façade, these
piezo springs generate energy via piezo ceramics. The energy can be used for building services such as shading, ventilating etc. In
addition, integrated actuators let the façade respond to varying wind loads: With moderate wind speeds, it generates energy, with
heavy wind speeds it self-adjusts to minimise wind resistance by optimising its shape. This prevents major damage and deformation, especially in high-rise buildings that are often subjected to heavy wind loads.
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Fully integral Façade
Imagined by: Nathan Volkers
AM ranking
Description
In this conceptual vision, the façade is made of a printed multi-material gradient structure that fulfils all functions in one continuous façade layer. Principally, this façade could seamlessly evolve into a fully integral building. The ‘Fully Integral Façade’ (FiF)
vision uses the benefits of ‘graded materials’ and ‘free-form design’ related to Additive Manufacturing. It covers most aspects of
façade design, although ‘free-form’ and ‘function integration’ are the most important criteria. The FiF fully benefits from 3D CAD
software with finite element methods built into it. Engineers design these façades with parametric models that can be fully optimised in terms of structure and functionality. For example, structurally the façade can ‘mimic’ nature’s solutions for structural optimisation such as bone structures. In terms of functional optimisation, gradient materials could be used that function as a hinge to
open parts of the façade. Thus, one material provides both stiffness and flexibility. The FiF is the result of a complex mathematical
3D model that determines where structural strength and other functions should be positioned. Mastering complex 3D modelling
becomes a required skill to design façades or buildings. The future fully integrated façade might be a complex formula, for which the
context and the user requirements define the parameters.
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Sphere within Sphere
Imagined by: Holger Strauß
AM ranking
Description
Derived from the Chinese ‘sphere within sphere’ idea of turned wooden spheres, this sketch elaborates the concept into a functionally integrated façade system. Scaling the modules provides extra freedom in creating applications with this feature – designed in
CAD, the size of the printed module is irrelevant; reaching from micro to macro.
Features integrated within the spheres could be pollen filters, phase change materials to store energy/warmth, insulating materials,
shading; a layer of printed photovoltaic foil could even generate electricity… Layering functions is a benefit for multifunctional façades.
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Mono Material Recycling Element
Imagined by: Holger Strauß
AM ranking
Description
Houses can be constructed from a mono-material, e.g. aluminium. Depending on the processing method, the material can exhibit
a great variety of material properties: foam, lightweight structures, solid, free-form. A house printed from a mono-material can be
fully recycled because only one material was used. Aluminium can be shredded and reprocessed as Rapid Manufacturing material.
Different ways of joining different parts on the surface will need post processing, such as welding, grinding, polishing, but this
results in a smooth watertight surface with no gaps.
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Active Insulation
Imagined by: Ulrich Knaack, Holger Strauß
AM ranking
Description
The goal of this concept is to provide our houses with the necessary insulation at the exact time when insulation is needed. Similar
to birds that fluff up their feathers to create an insulating layer against the cold, building structures could extend in wintertime to
achieve better insulation. Printed micro-structures could be used to fulfil this goal.
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Tissue Engineering Skin
Imagined by: Holger Strauß
AM ranking
Description
With the newly developed material of ‘printed’ human tissue, real skin can be generated from bio-organic material. The idea is to
employ the perfect performance of the skin for a building envelope. Water tightness, wind tightness, breathing and evaporation
could be achieved with one layer of skin. And insulation could be provided by growing hair on one side of the façade. By storing
organic material, the skin could even be self-healing.
The skin is mounted to a substructure (Mero-like system) with a terminal block and interlinked steel cables.
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§ 4.2.2 Direct Glass Fabrication
The Idea
Imagined by: Ulrich Knaack, Holger Strauß, Lisa Rammig
AM ranking
Description
While direct fabrication of materials such as plastics or metal is a sophisticated technology, Direct Glass Fabrication (DGF) is almost
unexplored although glass is one of the most fascinating building materials we know. It is strong but brittle, heavy but appears light,
and it is transparent. These properties have made glass into an important component of our built surrounding. It protects us from
weather influences, but it is not a barrier that cuts us off from our environment.
Today’s architecture is very much influenced by digital media and tooling software that enables us to create almost anything. However, it also poses increasing requirements on the building materials. For certain designs, free formed glass panes, each different
from the next, need to be cut to perfect dimension so that they can be joint accurately. This brings up the question as to why not
use additive fabrication methods for glass production. Additive fabrication with glass would enable the production of free formed
transparent building parts while eliminating the need for the traditionally very complex processing steps.
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DGF-Joint I
Imagined by: Holger Strauß, Lisa Rammig
AM ranking
Description
One step in the evolution of DGF would be the welding of glass panes instead of gluing them. The gap in between two panes is then
filled with a heated glass-rod in the same way as if using a hot-glue-gun. To assure a proper connection of the material, they have
to be preheated and then brought to a processing temperature. With this method jointing could be achieved, which leads to an
increase of design quality and to better maintenance conditions: a homogenous surface would allow for faster cleaning with less
effort and also bears less danger of leakages caused by bad sealing materials.
Another advantage is to be able to weld the glass panes on-site: to do so, small hand-held devices need to be developed. These tools
than need to be able to preheat, weld and anneal the glass structures. At the beginning of the process, the glass panes get heated,
the viscous glass is brought into the joint layer by layer and directly fused with the edge material. The heating and cooling parts
should lie flat on the glass surface.
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DGF-Joint II
Imagined by: Holger Strauß, Lisa Rammig
AM ranking
Description
With the priciple of DGF joints on-site also free form structures and shapes could be assembled in a mono-material way. To do
so, special free form connector pieces would bear all the complex deformations for the over all shape. In between those connector
pieces standard float glass could be filling the gaps. With the DGF-on-site handheld device, the joints would be done in-situ.
For glass, the tool has to be somehow able to heat the whole glass pane with a temperature difference smaller than 190 K in all
spots of the pane, which is a challenge. Alternatively another tool for heating the material could be deployed. The cooling part helps
to accelerate the process of hardening. It has to be relatively big, to guarantee a proper heat declension and avoid material deformations caused by ‘rest viscosity’.
This technology can also be applied to more materials: PMMA is already an available material for AM-Technologies. So a monomaterial joint for large scale acrylic-glass structures could be achieved by employing the joining-method of the DGF-principle
to PMMA. A hand-held tool is today used for PVC flooring, whereas a filament material is being fed to a cut-and-glue device and
perfectly cuts, joints and seals the flooring.
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DGF-Fishtank
Imagined by: Holger Strauß, Lisa Rammig
AM ranking
Description
If the requirements for large transparent structures demand the use of glass, but the structural capacities or production feasibility
do not allow for such large glass components, Direct Glass Fabrication might offer a solution:
In the case of an extremely large fish tank, for example, that requires 300mm thick glazing elements of specified dimensions, there
are no current production methods available. Acrylic glass could be used instead, but it does not offer the pure visual qualities of
glass. The better solution would be to use 3D printed glass to build up structures that withstand the water pressure. Optimised
structural shapes would offer material savings, and the load-bearing structure could be determined exactly according to the real
pressure load of the water, not according to the given limitation of traditional glazing element fabrication. Internal cavities could
be used either to reduce the amount of material needed, or to fill the structure with water to obtain the required weight. Digital
shaping of the glass could provide special effects such as fish-eye lenses or focal points that offer extra value for the viewer – e.g. a
3D porthole, made from a mono-material structure.
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Biomimicry Skin
Imagined by: Marcel Bilow, Holger Strauß
AM ranking
Description
Extra value from digitally implemented information can be gained with a bio mimicry façade. Interference structures on the surface
make logos or designed images appear on the façade. During planning, the desired design can be dragged-and-dropped onto the
façade with a special CAD tool (pattern, grid, logo, and lettering). A printed micro structure creates the interference on the surfaces
similar to how certain colours appear on butterfly wings. The light is emitted by the structures and the design appears through light
refraction. In combination with a lotus effect layer, the façade can be long-lasting and easy to maintain. The designs are not painted
but rather printed onto the façade surface.
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§ 4.2.3 Customization
Zero-Tolerance Refurbishment Façade
Imagined by: Tillmann Klein
AM ranking
Description
In refurbishment, tolerances are commonplace. Individually adjusted connectors for the new façade could be created with a mobile
3D scanner. The technology for 3D scanning of entire buildings and complex structures has long been used in industrial applications – such as the assembly of mega-scale structures for power plants or bridges. The data is transferred into 3D point clouds that
offer the possibility of reverse engineering of detailed information. Sophisticated software and computer hardware are capable
of handling large amounts of data; thus, hand-held applications for on-site scanning and engineering are available for existing
buildings or façades. By transferring the exact geometries of the building/façade with all its deformations and settlements now
offers the opportunity to individualise all necessary connectors and components for refurbishment. Such virtual planning means to
eliminate complex adjustments on-site, the new skin fits perfectly and therefore carries less risk of failure.
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Rotating Sunscreen
Imagined by: Marcel Bilow, Leonie Van Ginkel, Holger Strauß
AM ranking
Description
Avoiding heat transmission into our buildings is one goal to reduce energy consumption used today for conditioning of buildings.
Sun shading is one key to do so: by applying rotating disks with transparent and non-transparent materials, distributed in a controlled pattern, leads to distinct shading but still allows to have the look to the outside.
Using AM to print the rotating shading device changes the boundary conditions. The problem of replacement and maintenance
due to wear can be solved by designing a device where the moving parts do not touch each other at all, using the geometric freedom
of the process. Thereby, a magnetic trail would be implemented in the perimeter of the disk. If switched on, the disks float in the
casing. Each disk can be different in scale and pattern, because the design is independent of the production method.
Printing this device means that transparent, load-bearing and insulating material in the shape of glass, metal and glass fibre could
be printed in one process. The behaviour of these materials makes it reasonable to presume the development of this graded product.
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Snap- Façade Joint
Imagined by: Anna-Lena Waldeyer, Florian Winkelmann, Jasmin Lövenich, Katarzyna Kiersnowska, Rebekka Tegelkamp, Tina Schuster, Holger Strauß
AM ranking
Description
The idea behind this sketch is the combination of ‘snap and lock’ products from well known applications with AM performance for
facade joints. Facade panels could be mounted by a single person, because they are made from lightweight material and feature
an improved mounting system. This mounting system was developed from the basic adoption of the ‘snap and lock’ features and
further developed for various rear ventilated façade variations. The evolution in shape and function comes from engineering with
the AM possibilities.
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Customized Sound Absorber
Imagined by: Foteini Setaki, Holger Strauß
AM ranking
Description
The principle ‘Customised Sound Absorber’ fully exploits the possibility to individually adapt products by using Additive Fabrication
and a parametric design: After measuring the sound load in a space
(1), a unique profile of required absorbers is generated with a software
tool (2).
By changing certain parameters, the user can adjust the sound performance of the space to his or her individual needs. An algorithm is used
to determine the required number, size and shape of sound capsules
(3). The design can also be based on pixelated graphs that serve as an
abstraction base for the module. Various basic geometric shapes are
used as originating shapes for the absorber capsules, and are automatically joined and adjusted.
The modules are based on a coded building plan that, similar to a
puzzle, can be put together in only one manner. Thus, in addition to
the required surfaces for the Helmholtz resonators and the necessary
volumes of porous absorber materials, the topology of the module
which acts upon the sound reflection in a space is determined.
Using a fabber, the customer can ‘print’ the individual absorber
capsules (4) and join them into a decorative, highly individualised
sound wall (5).
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§ 4.2.4 Summarising assessment of the shown principles
With increasing depth and complexity, the probability of realising the sketched
principles moves into the far distance. However, they offer a sense of the ‘realistic
potential’ of applying AM; even against the background of the fact that technologically
they are currently not feasible. The ideas are complex and take a stand concerning
the new manufacturing methods, changed planning fundamentals, desired part
properties, the control of climatic influences and a new materiality of the façade.
§ 4.2.4.1
Façade technology
A more specified consideration is the hybrid ‘Snap Façade Joint’ where available
lightweight materials from the automotive and aeronautic industries serve as the basis
for a transfer into architecture. Assembly and load-transfer optimisation and therefore
resource friendly building comes within reach by optimising the joint technology. This
development challenges us to rethink the design of building technical details. But it
also requires an integrated use of design and simulation tools when developing such
components. And thus, this idea does not only change the product ‘façade’ but at the
same time planning processes, areas of responsibility and the role of the architect.
§ 4.2.4.2
Climate and comfort
As described by Bilow ([7] 2012), changing demands on the building envelope lead
to changing requirements for better building products. Against the background of the
economic and ecologic shifts over the coming years and the legal obligations for energy
neutral building6 ([9] [8] article 9: “almost energy-plus-houses as of 2020”), technical
solutions can find their place in the market that could be better or more effectively
realised with new technologies. Thus, the sun shading device described here was
6
The information was taken from: DIRECTIVE 2010/31/EU OF THE EUROPEAN PARLIAMENT AND OF THE
COUNCIL of 19 May 2010 on the energy performance of buildings;
Reference [8]: EU, Directive 2010/31/EU on the energy performance of buildings T.E. Parliament, Editor. 2010,
Official Journal of the European Union.
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conceived and developed as an integrated component that can only be realised with
technologies that are not yet available. But the effects and the functionality can already
be formulated as an intermediate step so that an initial prototype could be built with
current manufacturing methods.[10]
Figure 80
Bilow, Ginkel: manual prototype ‘RSS’
If developed strictly on the basis of AM, the product can be even further optimised.
An AM Envelope is generated from a seamless gradient material with numerous
properties. Simulation and functionally constructed components eliminate
unnecessary use of material and oversizing – with a creative freedom that is
independent of predetermined material properties and standard building products.
Against this background, the implementation of the Rotating Sunscreen in an AM
façade is the logically consistent application of these principles. The benefits that AM
offers demand that we create integrated functionality. For the Rotating Sunscreen
this means the possibility to use an optimised drive method, which, similarly to the
Transrapid train, is based on friction free magnetism.
For now, the RSS remains an AM vision exemplified in a small illustrative model that
does not feature technical performance properties. The prototype is a non-functioning
representation model because the relevant technology is not yet available.
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Figure 81
Left: rendering of the integrated sun shading device; middle, right: Images of the AM prototype; realized in different
materials with the PolyJet technology.
§ 4.2.4.3
Glass as a basic material for AM
The continuing desire for ever more transparency in our façades leads to further
development of the use of glass in combination with AM technologies. The fascination
of the material is unbowed – even while the discussion about energy savings continues.
The applications shown and the underlying principle are convincing; however, AM
should not be understood as a universal remedy but must be considered in a sensible
combination with sophisticated glass technologies. ‘In situ glass’ [11], ‘seamless
glazing’ and a ‘hand-held printer for glass applications’ are items that designers and
architects understandably wish for, and that drive further development.
§ 4.2.4.4
Individualisation
The ‘Customised Sound Absorber’ is a first in combining the ideas of mass
customisation, democratisation of the production and the future of AM technologies
in that it is based on a Do It Yourself (DIY) application to create an integrated (building)
product that enables improved building technical situations with freedom of design.
But this idea also shows that even in the future expert knowledge will be needed to
realise creative ideas. Programming accurate software tools with an intuitive user
interface that allows laymen to apply them correctly will remain expert knowledge.
Controlling the algorithms to achieve reliable results will also remain an expert task.
Using such expert knowledge by means of a fabbing system imparts a playful simplicity
that is also required for larger (building) projects. In the shown form, this idea is an
application for interior spaces. But the topics noise and sound are becoming a façade
issue: Why should we not use a sound absorbing layer on the outside of a building to
help reduce noise loads?
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An evaluation of the ideas demonstrates that they are all based on current thought
processes and the status quo of today’s technology and engineering. Thinking
beyond those boundaries proves difficult, and if done results in ‘wild’ ideas that seem
unrealistic. However, the potential of these ideas can be evaluated if looked upon in
retrospective and assuming technology advancements.
§ 4.3 Influence of AM on architecture
AM technologies open up a new world of product development. ‘Funktionales
Konstruieren’ (functional constructing) makes it possible to work from the desired
functions rather than having to realise an idea with products that are currently
available. Such paradigm shift turns the approach to product development on its head.
It is no longer critical to design according to available production methods (‘design
for production’), but rather possible to consequently realise a functional construction
(‘design for function’). This new way of designing should also be applied to the design
and the production of architecture. By doing so, architecture itself will change, so will
the processes of planning and realising it.
§ 4.3.1 From design to built environment
In traditional architecture, a large structure such as a building always emanates from
the smallest structural parts. Thus, an ‘uninhibited’ design is followed by the fact that
the future shape and execution of the ‘vision’ will be subjected to material building
construction related limitations: different areas of a glass façade, for example, are
divided into main, secondary, sub, and support structures.
Any structure has its own requirements and necessities; and only as a whole they
form the overall image that lies at the basis of the design. There is not one functional
envelope that fulfils all of the demands of client, planner and user, but rather a
complex, multi-part building element. What was designed as a homogenous whole
disintegrates into a conglomerate of (too) many individual parts due to narrow
boundaries in materiality and numerous realisation-related restrictions.
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And this consideration does not end with a separation into different layers, but is
continued to the component parts of the individual layer: a ventilation wing, for
example, consists of fixed as well as movable parts, must be opened as well as locked,
must fulfil load transfer and requires a certain degree of freedom that will allow its
functionality.
These functionality related requirements bring with them an increasing complexity of
the components.
AA 720
P 3 -21
LM 4201 -DK/-E WK 3 ESG, Beschlagsübersicht und Einbaumaße
LM 4201 -DK/-E WK 3 ESG, hardware summary and assembly dimensions
This drawing underlies copyright and proprietary rights of
ALCOA Aluminium Deutschland Inc., whose written approval
for use, reproduction and publication to third parties.
All rights reserved.
Diese Zeichnung unterliegt den Urheber- und Eigentumsrechten
von ALCOA Aluminium Deutschland Inc., deren schriftliche
Genehmigung erforderlich ist für den Gebrauch, die Vervielfäligung
und die Veröffentlichung an Dritte. Alle Rechte vorbehalten.
a - 577 (a > 1150)(Flügelgewicht > 100 kg)
a - 577 (a > 1150)(vent weight > 100 kg)
S3b = (Schere Gr. 35 + Zusatzschere) = a - 856
S3b = (stay Gr. 35 + additional stay) = a - 856
S3 = (Schere Gr. 20) = a - 338 (a = 500 - 680)
S3 = (stay Gr. 20) = a - 338 (a = 500 - 680)
S3 = (stay Gr. 35) = a - 506 (a > 681)
Beschlageinbau
installation fittings
6 mm load-bearing thread length necessary
The purpose of the drawing is only for information.
ALCOA Aluminium Deutschland Inc. bears no responsibility for
exactness and completeness. The workman remains responsible
for correct and safe processing of Alcoa products.
Der Zweck dieser Zeichnung dient lediglich der Information.
ALCOA Aluminium Deutschland Inc. übernimmt keine Haftung
für Richtigkeit und Vollständigkeit. Der Verarbeiter bleibt
haftbar für korrekte und sichere Verarbeitung der Alcoa-Produkte.
6 mm tragende Gewindelänge erforderlich.
Änderungen vorbehalten.
subject to changes
Stand 08.2010
issue 08.2010
O 10 mm Nocken
O 10 mm cam
S3 = (Schere Gr. 35) = a - 506 (a > 681)
3) Ausnehmung der
Überschlagdichtung.
Mindestdurchgang für
die Beschlagteile 4 mm.
4) Ab Flügelgewicht 100 kg
(für Bohrlehre 271 907).
3) Recess of the estimate
gasket. Minimum passage
for fitting parts of 4 mm.
4) Starting from vent weight
100 kg (for jig 271 907).
Schließteil E (13) vor dem
Zusammenpressen der
Rahmenprofile in die Beschlagaufnahme erneut
einschieben. Einbaumakierung beachten!
Before punching of the frame profiles put the closer
pieces into the fitting groove.
Please notice installation marking.
5) Rahmenbohrung 4,2 für
Senkschrauben M5 x 13 (15) vorsehen.
5) Frame drilling 4,2 for countersunk screw M5 x 13 (15).
AN ALCOA COMPANY
Figure 82
Mounting details for a standard window by Alcoa ‘AA-720’. Imagery and illustrations from Kawneer-Alcoa digital catalogue, Issue
10/2010.
When looking at a high-rise building project, this same segmentation can be found in
all building parts. From the building shell to interior finishing, the highly technological
material mix brought together at the construction site hardly bears resemblance
to the distinct components shown in the original design. Simple attributes such as
surface design, chromaticity, joints and edges are realised with great technical effort.
Complicated composite parts are created that combine numerous individual parts,
materials and properties.
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The examples of recently built architecture have in common that the realisation
of the underlying visionary CAD designs are still coined by today’s technological
restrictions. Thus, after creating a unified, homogenous overall design, the structure
must be divided into transportable small components. The requirements for the
individual building parts such as roof, wall, foundation etc. are broken down into small
components in the planning process, and then reassembled at the construction site.
The result is one large unit that, upon closer inspection, can be broken down into its
constructive parts.
The conventional nodal point of a typical system façade also consists of a multitude
of individual parts. Assembling all of the components requires a large number of
fastening devices which in turn results in a high number of process steps during
assembly. Many parts mean many sources of error and increased maintenance
requirements. During optimisation, more and more functions were added to façade
systems; leading to more and more complex parts.
Considering the much emphasised shortage of natural resources, recycling plays an
important role in this context as well. It can speak for or against establishing new
manufacturing methods – AM is not a ‘green’ technology. However, developing
functional parts with AM can result in material savings and reduced material diversity.
[12]
§ 4.3.2 Toward built representations
The development of CAD and CAAD software is critical for today’s architecture.
Architectural designs from around 1920 show parallels to current CAD architecture. On
one hand this is due to a recurring stylistic vocabulary, such as is known from fashion.
On the other hand, the reason is that architects of all times have thought of buildings
as organic analogies. All eras show similarities to ‘grown’ structures, sculptural shapes
and inspiration derived from flora and fauna. However, the majority of these designs
remained utopian designs that were never realised. Noticeable examples are the
utopian city crown (‘Stadtkrone’) designs by Scharoun and Taut, as well as the drawings
by Hermann Finsterlin and Erich Mendelsohn (see [13]), but also the ‘Walking Cities’
by the architect group archigram in the 1960ies, none of which were ever realised as a
large building project.
Round, curved, free forms are difficult to plan, realise and assemble. On one hand
this is due to any material’s tendency to try to maintain its original directionality, for
example during bending. On the other, because a two-dimensional representation
can never capture or show all aspects of a given building part. Rafael Moneo speaks
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of “forgotten geometries lost to us because of the difficulty of their representation”
(citation from Branko Kolarevic: “Architecture in the digital age” [14]).
Another factor is the human being. Most constructions are joined and assembled at
the construction site. The craftsmen involved and the machines used can better handle
orthogonal components. Maybe this is the reason that only a few of the utopian designs
of the last century have been realised.
§ 4.3.2.1
Mendelsohn, Einsteinturm
One of the built designs of expressionistic, free form is Mendelsohn’s ‘Einstein Tower’
from 1920-1924. It resembles a free-formed sculpture more than a functional building.
Mendelsohn skilfully combines the necessary spaces with lively, amorphous shapes.
Conceptionalised as a reinforced concrete structure, the part of the tower above the
plinth was built with conventional brick building methods however, due to problems
when trying to create the unevenly curved formwork. The surfaces were then plastered
with rendering to create a uniform surface. The inconsistent use of the materials
caused the building to deteriorate early. Building humidity and varying material
thicknesses and expansion properties led to chipping off and cracking. As early as in
1927, metal plates were applied to counteract the problems. But even after various
restoration measures the building continues to require constant renovation.
(see [15] [13] [16]).
Figure 83
Left: Erich Mendelsohn, Einstein Tower, Potsdam, 1920-24;
right: elevation after the restoration in 2000; b.) detail of the entrance.
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Today, the development and use of new planning tools and new materials enables us to
realise designs that were difficult to execute at the beginning of the twentieth century.
Particularly the field of building with reinforced concrete has greatly improved, for
example in the areas of concrete with non-metal reinforcement [17], self-compressing
concrete and high performance binding agents with diverse properties. Thus, realising
Mendelsohn’ design in monolithic fibre concrete would be less problematic today.
Almost all material groups have been further developed and therefore offer greater
architectural freedom of design. Building parts made of glass fibre reinforced plastics
(GRP), carbon fibre reinforced load-bearing structures and the use of sophisticated
specialised plastics (for example PEEK) open up unimagined possibilities.
§ 4.3.2.2
Cook & Fournier, Kunsthaus Graz
To create striking large-scale structures that serve as a branding opportunity for a
city has become known as “Bilbao effect”.[18] Form a formative point of view, these
extraordinary architectural designs play with long and close range effects, or the
disintegration of a large-scale shape into a conglomerate of building stones when viewed
from close up. This is also true for Kunsthaus Graz by Peter Cook and Colin Fournier.
The Kunsthaus, in popular parlance called the ‘Friendly Alien’, is an example of the
so-called liquid architecture - an amorphous, free-form design [19]. Some see the
building as a late realisation of the visionary archigram designs of the sixties, with Cook
and Fournier having realised their visions in a ‘new building’ icon.[20]
Figure 84
Left: view of Kunsthaus Graz in the middle of Graz, Austria. A ‘Friendly Alien’ in a historical setting.
right: close-up of a ‘Nozzle’; cladding was done in PMMA panes with point fixations..
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With its eye-catching shape and extraordinary appearance the Friendly Alien attracts a
great deal of attention. The design clearly shows that it was conceptionalised in virtual
space. The building does not want to fit in, but rather distinguish itself with its unique
free form.
For Colin Fournier, the predetermined step into the 21st century is the change of
architecture into 3D architecture in combination with 3D production.[21]
But because this process is not yet complete, the realisation of this project required
dealing with current production realities.
The façade appears to be the skin of the Kunsthaus and, on closer inspection, dissolves
into a multi-layered, complex and fragmented structure. It consists of more than 1000
individually shaped acryl glass panels and 6000 here for necessary point fixtures as well
as an elaborate load-bearing structure.
The components for such a construction are produced individually from available mass
products. Often, financial reasons prohibit the use of individual building products. It is
expensive to get certification for a new building material, and the process entails great
administration effort. Therefore, tested products are typically used, which however
results in compromised solutions for particular building projects.
§ 4.3.2.3
Gehry, Walt Disney Concert Hall
A pioneer in applying digital information to depict and realise complex buildings, Frank
O. Gehry showed that the way in which architecture is conceived, projected and built
has been changed by the digital revolution.
His project ‘Walt Disney Concert Hall’ in Los Angeles is the example that shows the
planning office’s most advanced technical development. Deriving its first projects
such as the Guggenheim Museum in Bilbao, the planning team around Gehry created
a digital workshop. This digital workshop was necessary to realise complex projects
without analogue drawings and the continuous transfer of information between the
parties involved in the realisation. Irrespective of the design quality of an architectural
project, the method of execution by means of digital tools is a consequent step
toward a new method of realising an architectural task – all of the information is
compiled in a parent file; all changes, adjustments and tests are done on the same
model. The architect manages this file – analogous to the historic master builder –
and thus returns to be a central institution of the building project, even if in a more
abstract manner than was the case conventionally. By using the data for planning as
well as directly producing the work, the architect returns close to production and can
control and influence it and possibly adapt it to architectural demands. Transferring
technologies between hitherto unrelated industries becomes easier, and promotes a
more accurate representation of the design idea into built reality.
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Paradoxically, in its renaissance approach of unifying planning and craft, the new type
of collaboration leads via free-form and Blob architecture back to the ideas of Bauhaus;
with an architectural expression that consistently promoted clear, straight lines and
repeatable elements for the benefit of serial production and that in its ‘Gestalt’ directly
opposes the seemingly random forms of Blob (or liquid) architecture.[22]
Figure 85
Left: view of Walt Disney Concert Hall, Los Angeles, California;
right: Close-up of the primary structure that was built in order to allow for the free form shape. Cladding is done in metal plates,
fixed to substructure.
§ 4.3.3 Potential for improvement using new technologies
The free-form possibilities that CAD software offers not only change the method
of designing but also the design itself. In most cases the 3D data records are very
large because they usually include specifications for materiality, type of execution,
prefabricated parts as well as lighting, shading and ventilation. Some offices already
use this data for immediate realisation, for example to process formwork drawings for
in-situ concrete constructions, or to create cut plans for façade cladding.[23]
But realisation is still based on the limited possibilities of today’s production
techniques. The designs are translated back into realisable components, meaning
that production determines design instead of design determining production. In spite
of the changes in the design process, daily routines on the construction site have
not yet undergone fundamental changes. Naturally, the possibilities of accurate and
complex processing of execution planning are reflected in the increasingly impressive
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results. But a design can only be as good as its later realisation on-site. The building
industry employs ever more high-tech products to cope with the greater challenges
of digital designs. Even though some industries segments already employ advanced
technologisation and therefore simplification of the production process, the building
industry does not yet offer a simple translation of design data to product. The
possibilities of the new technologies are merely used as a means to make conventional
building construction easier; not to fundamentally change the building task.
The examples show that the digital design directly influences the formative vocabulary
in architecture: modelled free forms are realised into buildings – creating Liquid
Design. Without computer simulation and precise CNC manufacturing, these forms
could not have been realised.
With the increasing use of 3D applications, Additive manufacturing (AM) also comes
to the fore of architects and others concerned with building. The applications in this
field are still limited to the generation of printed 3D architecture models. But the
advantages of AM to produce models, façade elements or entire buildings are the
same: production without manual screwing, gluing, joining and fitting.
Seamless production from the digital design, meaning a true CAD-CAM work process
is not yet possible. AM technologies might be a solution to do justice to these designs.
Relevant AM methods must be made usable for serial production and large-scale
applications in order to be applicable to the building industry.
Extraordinary architecture is in the public eye. It benefits from new developments. It
represents approximately only three to five per cent of the overall building volume; but
will always be the motor for innovation of design and construction.
§ 4.3.4 Mass Customization
An examination of the developments in the digital world shows a close link between the
different consumer goods markets. CAD and CAM also change the working methods in
architecture. In order to illustrate the connection between information technologies
and AM technologies, we must examine a development that is a result of these new
fields: Mass Customisation (MC).
Mass Customisation is a composition of the terms ‘Mass Production’ and ‘Individual
Customisation’.[24] It is the goal of the consumer goods industry to use MC to offer
individualised products at the price of mass products. MC fulfils increasing customer
demands for personalised products. However, due to cost issues, true individualisation
(so-called “Core Customisation” [25]) cannot be realised with the manufacturing
technologies commonly used today. Therefore, MC offers a certain degree of
individualisation, which, however, upon closer examination is a modification of mass
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products. One such example can be found in the automotive industry: when ordering,
the customer chooses an individual combination of numerous available options. The
selection of colour, wheel rim, accessories and extra equipment results in a product
that is specially configured for a particular customer. All cars of one series are based
on the same base modules, but there are many variations within the series of a model.
However, the customer has no influence on the actual design or function of individual
components because they are conventional components that were prefabricated with
conventional production methods. This leads to the usual high cost levels (production
means, inventory) that can only be regained by selling large quantities.
(see [25]).
Such limited individualised fabrication can be enhanced with AM. Assuming that the
difficulties still inherent to AM methods (material comparability, processing speed
and component size) could be eliminated, MC could evolve into true individualised
fabrication. With regards to the example from the automotive industry this could mean
that individual body scans could be used to make customised seats. These seats could
be produced individually with AM. Not only the colour and the type of item could be
influenced but also the shape and form.[25] With AM it will cost approximately the
same to produce two different seats, if the quantity of seats produced is similar. But the
overall effect is added value for the customer.
CO2 emission is another topic currently discussed and evaluated. One of the
arguments for introducing AM as a production method is to possibly reduce the CO2
footprint by exploiting regional production. Currently, the shipment of consumer
goods accounts for five percent of global CO2 emissions.[26] Also, the new method
of designing that is inherent to AM and the resulting products make it possible to
manufacture in a more resource friendly manner. Light weight structures, for example,
can reduce energy and resource consumption while maintaining equal component
performance through the use of less material, less weight, and shorter processing
times (theoretically dependent of the necessary building volume). Still, it remains to
be a theoretical comparison because we do not yet have an overview over all of the
production parameters of AM. Current estimates are that AM production is up to 50
times less effective than comparable building volumes produced with die casting (per
kilogram, per component). The same is true for a comparison of DMF components with
turned metal parts. The potential advantage only becomes visible if we consider the
overall energy consumption in a life cycle analysis. Lighter components in aeronautics,
for example, can lead to less fuel consumption and therefore energy savings. Also,
the new technologies could be used to conduct hitherto impossible repairs of high
value parts; resulting in less waste. In terms of sustainability aspects, this shows an
advantage for the AM technologies. Some research projects even assume that they
enable a development toward production with a reduced CO2 footprint (research
project ‘ATKINS – Rapid Manufacturing a Low Carbon Footprint’ [27]).
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Initial results show that it is possible to reduce CO2 emission by employing AM. Hereby,
metals show the greatest potential; while the SLS technology also shows potential if the
issues concerning recycling of un-used but heated material are solved. We must follow
a holistic approach and therefore it is essential to fully exploit the freedom in geometry
and design for part optimisation. In terms of shape and weight further CO2 reduction
is possible by designing slender geometries. Also there is a great economic interest in
optimising processes with metals, but repeatability and process speed must be further
optimised.[12] [28] [26]
The sustainability of intensively individualised products still needs to be evaluated
in the market, for example in terms of a potential resale of such items – the perfectly
customised car seat might be difficult to resell. A product can be customised to the
demands of an individual buyer, but aspects relating to return warranties or exchange/
return policies will be challenging.
All areas of the consumer goods industry offer input programs, so-called configurators
that allow the customer to individually configure a particular product. This is done
under the assumption that a number of customers are willing to pay more for the
advantage of being able to individualise the product. Standard products remain
available for all other customers. The companies benefit from immediate market
access by offering such active customer involvement through feedback and monitoring
of the individual products. Exploiting the customer’s input (‘Open Innovation’) enables
the manufacturers to lower the cost for development and provides them with the
assurance that their products meet the demand. MC aids in reducing the required
inventory and the risk of unprofitable investment caused by an unaccepted product.
(see [29]).
But a growing number of architectural mass products and prefabricated houses is also
a development that results from the possibilities that CAD, CNC and ultimately AM
technologies offer.[30] The client chooses dormers, gazebos, porches and carports
from a variety of options to create his or her personal dream house. CAD allows for
marketing via a webpage, and a combination of CAD and CAM facilitates production.
The houses are built to order in a modular manner following the principles of Mass
Customisation. With these individual configuration options, the design quality of such
buildings can only be controlled by offering only high quality options and limiting the
degree of individualisation. This is done with the so-called Black-Box System.[25]
Hereby, the system controls the configuration with certain parameters (for example
maximum, minimum) and resets a value to a predefined default if the user has
entered values that are too low or too high. The user uses the configurator to configure
a product according to his or her wishes; however, the influence he or she has on the
individual parts is limited. In order to achieve a certain level of quality, we will continue
to need designers and planner whose expert knowledge distinguishes them from the
home user. For buildings, this is a necessity not least because of the required stability,
usability and feasibility. Individualisation without such a controlling authority would
lead to over-individualisation.
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Even though future developments of 3D systems will lead to easy and intuitive use, the
complex processes of translating a 3D model into a physical building are specialised
services that cannot yet be satisfactorily accomplished by laymen.
“The implications of mass-customisation for architecture and the building industry
in general are profound. As Catherine Slessor observed, ‘the notion that uniqueness
is now as economic and easy to achieve as repetition, challenges the simplifying
assumptions of Modernism and suggests the potential of a new, post-industrial
paradigm based on the enhanced, creative capabilities of electronics rather
than mechanics.’ In the modernist aesthetics, the house was to be considered a
manufacturing item (“machine for living”). Mass production of the house would
bring the best designs to a wide market and design would no longer cater to the elite.
That goal remains, albeit reinterpreted. The industrial production no longer means
the mass production of a standard product to fit all purposes, i.e. one size fits all.
The technologies and methods of mass-customisation allow for the creation and
production of unique or similar buildings and building components, differentiated
through digitally-controlled variation.”[31]
New technologies can only come to common use if there is a large enough market for
them. And it is easier to create such markets by fulfilling the demands of the general
public (see [25]). Similarly, architectural mass markets break the path for an acceptance
and therefore use of CAD and AM technologies in the façade and architecture in general.
MC used for buildings can make high quality designs accessible to a broader audience
and eliminate the exclusivity reserved for a elitist minority (see [31]). The creative
freedom of design that CAD offers influences the appearance of our built environment.
§ 4.4 Economic efficiency of AM
This work has not answered the question of true economic effectiveness of AM
technologies as they relate to façade planning and realisation. This aspect of a holistic
treatment of the topic can only be examined peripherally because the realisations of
the project results presented here depended on AM service providers.[2] If AM is to be
integrated into real production chains it must be considered a customary application
and overcome its image of an exceptional technology! Economic efficiency with AM can
only be achieved if common use has brought all advantages and disadvantages to the
surface. Only then can all savings potentials be exploited and a maximum utilisation
of the entire potential ensured. For each façade project, this must be done for a
specific AM system considering factors such as process chamber, production time, and
optimum orientation within the process chamber.
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Initially, the investment for an AM system in the production chain of a façade
manufacturer disproportionally exceeds the production quantities achievable with the
sytem. However, a longer production period would provide a truer calculation of the
cost for AM. A direct comparison of today’s standard building parts with optimised AM
building parts is impossible. Opening up technological potential must be followed by a
monetary evaluation of the performance characteristics.
Besides all aspects of technical feasibility, economic efficiency will always play an
important role when deciding for or against integrating AM into production.
To justify the procurement of an AM system with the production of components alone
that cannot be manufactured with any other method than AM is too narrow a view
of the matter. Rather, considerations should include various aspects of one’s own
production: Where can a sensible application of AM technologies generate added
value? Which other benefits besides realising free forms and geometrically challenging
components can be achieved?
Motivation to procure an AM system can be driven by some of the following factors:
§ 4.4.1 Break-even point
The trend in AM market goes toward producing end use parts. Hereby it is important
to conduct an economic efficiency analysis to be able to compare AM technologies to
the conventional methods for mass production. Neil Hopkinson has been engaged in
this issue for many years.[25] He has examined processing aspects related to defined
quantities and a ‘break-even point’. Such considerations must be conducted for each
AM process separately; in fact, for each part geometry. In general, the prime reason
for such considerations is to estimate the specific quantity at which it makes sense
for AM to compete with die casting, for example. Initially, these considerations were
merely based on the size of the part, not on the expected increased performance of an
improved part made with AM, or the product benefits measured over its entire lifecycle.
Independently hereof, such studies as well as their results must always be based on
the newest methods and system technologies available. Thus, parameters and results
change at the same rate as the system technology itself.
Finding about production output can only be provided by the large service providers in
Europe. Manufacturing facilities are also known as ‘Sinter Farm’ with a 24/7 operation
of AM production. The increasing relevance in the market shows in the fact that Apple,
for example, lets service providers produce protective covers for its iPhone with AM. The
initial lot size is specified at 27,000 pieces to be distributed worldwide. The required
geometric shape of the protective cover does not permit any other manufacturing
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techniques than layered, generative fabrication, and therefore excludes other methods
of mass production.[32]
The fact alone that parts produced with AM are adopted by a market leading supplier
allows a conclusion to be drawn about the future development of AM as part of
the production process. This must be based on the assumption of great process
reliability and according high repeatability of the individual parts. Market leader FKM
Sintertechnik GmbH, Biedenkopf, Germany is one of the first companies to offer the
SLS method as a professional service. Expert knowledge based on a deep insight into
the processes running on AM systems offers the freedom to test new markets.[33]
§ 4.4.2 Possible savings related to material consumption and weight
Concrete improvements, for example in the area of performance properties crystallise
in addition to the possibility of easily changing the shape and appearance of AM made
parts. Possible savings related to material consumption and weight resulting from
shape optimisation and the use of light weight structures (see § 2.5.2.3) opens up
new markets for AM as a production method. In aeronautics, a reduction of weight is
directly linked to fuel consumption. The technologies are thus directly related to the
current discussion about preserving resources, CO2 emissions and environmental
compatibility. The example of parts manufactured for the aeronautics industry shows
possible fuel savings, even though the initial cost to produce such parts made of high
performance plastics (for example ‘PEEK’ with the SLS method) or metals (for example
aluminium with the DMLS method) are higher.[34]
§ 4.4.3 Batch size one
Another advantage is the possibility of manufacturing product series with a batch size
of 1. This means that production of small series or even single pieces is economical.
With traditional manufacturing methods such small batch runs are not realisable. AM
allows for customised products according to customer specifications – single products
without added cost, single products at the price of mass products (see [2]).
AM materials used today also allow to closely imitate the properties of ‘standard’
methods. This allows more freedom in the development of mass products. On one
hand it is possible with AM to run more optimisation cycles in a shorter period of time,
resulting in a modified prototype that continuously exhibits higher product quality; on
the other hand a closer and more immediate collaboration allows for better testing and
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therefore more sophisticated development before launching a product. In addition,
consumer surveys can be conducted at an early stage of the product development
which minimises the risk of misdevelopment. This results in greater customer
satisfaction because the very first generation of a mass product has already undergone
extensive development. And marketing a new product using realistic prototypes can
lead to higher acceptance and demand in the market.[35]
§ 4.4.4 Development cost for introduction to the market
In the consumer goods industry, AM is now being employed as a pre-marketing
tool when introducing new products to the market. The very first edition of a newly
developed product can be tested in the market without the traditional development
cost. With sufficient demand the product can then be produced with conventional
methods. Thus, with AM a product can initially be distributed in limited numbers,
which allows for optimisation before investing in expensive tool sets for mass
production (see [25] [36] [37] [38]).
It is true for all areas of Additive Manufacturing that the cost for product development
is significantly lower than with traditional methods. With Additive Manufacturing, the
price is no longer influenced by difficult product or tool geometries. Before, it was the
complexity of the model that determined the cost. With AM, this is no longer the case.
Growing competition in all areas of the AM market results in lower prices. Ambitions to
make the technology accessible to a larger audience are understandable considering
the expected market for AM services and complementary market areas. It becomes
increasingly attractive for producing companies to look into the technology and to
invest in an AM system to complement conventional manufacturing processes.
§ 4.4.5 New markets
The awareness and understanding of the AM technologies has grown strongly over
the past years. The consumer goods industry uses additive methods to individualise
products, the movie industry uses them to create props and masks, the computer
games industry uses them to support their marketing strategies, and the aerospace
industry uses printed components in aircrafts. Many different protagonists in the
development talk about the methods; the DIY market is booming. New trend and
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technology analysts have been watching the methods for some time now and adjudge
it great potential.
On one hand it is good that the large renowned market studies and lists of “emerging
technologies” finally include the AM technologies. On the other hand, these potentials
must be exploited to open up a new market. In this context the architect’s or planner/
designer’s position is weak. Actual decisions to continue the implementation of ‘3D
Printing’ must come from the industry itself. Ultimately, the decision as offered in
Gartner’s Hype Cycle [39] as a tool to determine whether and, if so, when a technology
is considered to have a good chance of success, is based on economic factors. Economic
efficiency always has to do with unforeseeable developments as well, and therefore
involves a risk that can have a positive or negative monetary impact.
Investing in the new technologies poses a risk for any company. The capital expenditure
for equipment to produce metal parts (DMF) starts at approximately €500,000 and is
open-ended. One has to have a good reason or argument in favour of AM technologies
to justify such an investment. It is not easy to find such arguments for a particular
project alone; but while the building envelope becomes an increasingly important
part of the building project, the share of the entire construction sum for the façade
increases as well. An AM system might self-finance with just a few projects. An
intensive discussion about such investments and the here form resulting pressure to
ensure economic operation of the system can be another driving force to try something
new.
Further information about economic efficiency and market relevance can be found in
appendix A I / New markets from AM.
§ 4.5 Summary chapter four
Combining CAD designs with AM technologies enables digital fabrication, and the
possibilities of digital production are adapted to the possibilities of digital planning.
Design-oriented realisation using digital processes creates a direct connection between
design and production (‘file-to-factory’ process, see [31]). In the beginning stages of
digitalisation there was the question of the realisability of complex CAD shapes. Today,
the question is no longer whether, but rather with which tools such shapes can be
realised. Besides the subtractive and formative methods, it is the additive methods that
allow for a variety of shapes and functions.
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The sketched ideas show applications that generate a functional added value from
the AM methods. Considering the current state of the art of AM, the open issues
related to the technical developments of the principles remain. They offer a field
of work for subsequent research into the future of the building envelope. The
suggestions for AM Envelopes can be used to illustrate and evaluate the potential
of AM for façade construction. Such building envelopes can be accurately realised
with AM. The solutions can be individualised by simple changes of the data records
while maintaining the quality of the realisation. The building technical risks when
realising bespoke AM Envelopes can be minimised, because the assurance lies in the
manufacturing process, not in the parts used.
Even if the economic aspects of AM technologies cannot be finally judged today, still
the major developments in the AM market and in the changing building industry
lead toward more effective solutions in building envelopes and building technology.
Here the shown aspects of time-to-market, regional production or light weight parts
highlight a few possible ways to combine new technologies to more responsible
solutions.
References chapter 4
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[12]
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era21/index.asp?page_id=98 2005.
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Pehnt, W., Die Architektur des Expressionismus. 1998, Ostfildern-Ruit: Verlag Gerd Hatje.
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Tietz, J., Geschichte der Architektur des 20. Jahrhunderts. 1998, Köln: Könemann Verlagsgesellschaft mbH.
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VDI Bautechnik, Jahrbuch 2008. 2007, Düsseldorf: VDI Verlag.
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Syring, E. www.architop-bremen.de, Vom Jugendstil zu den Blobmeistern – Organische Formenbezüge in der
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museum-joanneum.at/de/kunsthaus/das-gebaeude/statements/colin_fournier.
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Van-Bruggen, C., Guggenheim Museum Bilbao. 1997, New York: Gerd Hatje Verlag.
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Piller, F.T. Mass Customization & Open Innovation - A Blog by Frank T. Piller. [cited April 2012]; Available from:
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Hopkinson, N., R.J.M. Hague, and P.M. Dickens, Rapid Manufacturing. An Industrial Revolution for the Digital
http://mass-customization.de/.
Age. 2006, Chichister, England: John Wiley and Sons, Ltd.
[26]
Hague, R. Atkins Project. 2007 [cited 2011 September]; Available from: http://www.atkins-project.com.
[27]
Woodcock, J., Additive Manufacturing and the Environment in tct magazin. 2010.
[28]
Reeves, D.P. Environmental cost reduction using Rapid Manufacturing. in tct live 2008. 2008. Birmingham.
[29]
Stampfl, N.S., Mass Customization: Maßgeschneidert vom Fließband. März 2007, perspektive: blau,
[30]
In wenigen Minuten zu Ihrem Traumhaus, Konfigurator von Kern-Haus, http://www.haus-konfigurator.de/.
wirtschaftsmagazin.
[cited May 2008].
[31]
Kolarevic, B., Architectur in the digital age: Design and Manufacturing. 2003, New York: Spoon Press.
[32]
Blöcher, J. (2012) Rosarot und himmelblau. 2.
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Dehnert, F., FKM to produce 27.000 I-Phone Covers on viable basis, t. author, Editor. 2011, Frank Dehnert, CEO
FKM Sintertechnik GmbH: Frankfurt
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[35]
Bullis, K. GE and EADS to Print Parts for Airplanes. [cited May 2011]; technology review newsletter].
Objet-Ltd., Top 5 reasons to integrate 3D Printing into your Product Development Lifecycle, in tct magazin.
2011, Duncan Wood: Tattenhall, UK.
[36]
Wohlers, T., Wohlers Report 2007, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2007: Fort Collins, Colorado, USA.
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Glass, N. fabtory, http://schnellemodelle.de/. [cited April 2008].
[38]
RT Reprotechnik.de GmbH, rapidobject.com, http://rapidobject.com/. [cited April 2008].
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Fenn, J., Raskino M., Mastering the Hype Cycle - How to Choose the Right Innovation at the Right Time, ed. I.
Gartner. 2008: Harvard Business Press Service. 237.
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5 Conclusion
This work is aimed at fathoming the potential of Additive Fabrication to change façade
construction.
In order to do so it documents the technological possibilities of the AM methods
as they relate to façade technology. Based on the executed projects, the number of
different methods available was reduced to five AM technologies that seam relevant
for façade applications. But this kind of potential evaluation must be redone for each
new project because the great variety in AM technologies brings with it an equally great
variety in performance.
Based on these descriptions and evaluations of the AM technologies, requirements
placed on the building envelope were formulated and put into direct context with
available AM technologies. Subsequent developmental steps toward an AM Envelope
were derived from a list of the required areas of performance as well as an examination
of the historic development of the façade technology. It is important to clarify that
these developments always require the potential for improved parts as well as for
improved system technology, and therewith influence both directions of development.
As core of the research, a research project studying the production of façade components
with AM was conducted. The results were documented and, after chronological
classification, linked to developmental steps and their realisation (see § 4.1).
To link the AM theory to façade reality, convincing AM prototypes were developed and
manufactured. The prototypes make it possible to make the AM methods accessible
and – literally – tangible to a professional audience. The responses consistently confirm
the power of the materialised ideas and thus support the core statement of this work
which is that AM technologies bear great potential to change the construction methods
of façades. The type of assistance that every participant requires in the process of
developing an AM Envelope in order to fully exploit the potential that was described. It
became apparent that a detailed documentation of the feasible and the impossible by
means of guidelines for the different process partners is necessary. Hereby, the content
must be matched to the different demands of the planning and production process.
These guidelines are the basis for a subsequent scientific discussion of the topic ‘AM
Envelope’ and the translation into built reality.
In order to examine the research results in terms of a possible built future, additional
visionary ideas and conceivable applications were added to the product-oriented
results. The possible impact of the AM technology on façade construction can be
derived from an entire line of ideas – closely connected as well as further removed
from the AM Envelope – by means of the established time line (see § 4.1) and an AM
ranking showing six important aspects of the presented ideas (see § 4.2).
179Conclusion
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The potential was discussed and evaluated with future AM users, which in turn led to
more ideas and specific visions.
§ 5.1 Answers to the sub-questions
Since the content of the chapters of this work is oriented on the proposed subordinate
questions of the hypothesis, the following provides compact answers to each. The
individual chapters provide more detailed information; but the following section offers
a generalised summary that can be used to assess the potential.
Chapter 2:
• What technical possibilities for façade construction are available today with AM?
The description of the status quo of the technical possibilities of AM (see § 2.2)
shows the large number of different technologies, but also the large number of
variants of basically similar technologies used for very specialised applications.
Since its beginning in the late 1980ies, the development progresses very
dynamically and shows strong and consistent growth. Two fundamental decisionmaking options can be derived from this consideration and the description of
the most common AM principles: manufacturing components with plastics or
with metals. Following this decision, appropriate system technologies can be
found for any application under consideration of the relevant planning goals. The
fundamental differentiation between the two large material groups inevitably leads
to the demand of adapting existing technologies to a particular product task.
180
•
Which changes do AM technologies have to undergo to be applicable to façade
technology?
In order to make an impact on building technical applications, the technologies
must evolve from sophisticated ‘prototypers’ to reliable production tools.
Batch-size independent production of precisely equal components is mandatory.
As are certification and approval of the technologies to ensure safe and secure
building technology. Besides these aspects concerning product liability, the system
dimensions must be adjusted, processing speeds reduced, and manufacturing
cost lowered. The last aspect is and will remain to be the decisive factor influencing
an introduction in a new market. And at the same time it is the main criterion for
exclusion when considering whether or not to manufacture with AM.
•
Which external influences can cause such changes?
Important stimuli for technology changes come from the industry: Rapid
Prototyping technologies for example could only be developed after high
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performance lasers reached marketability; today, new energy sources or a significant
increase in performance of the laser can create new impulses. An AM independent
development in mechanical engineering, material science, process development is
also conceivable, as is a direct demand from a different industry.
•
Which technical requirements are posed on an AM Envelope?
To justify the development of an AM Envelope, the performance properties of
the new building envelope must clearly supersede those of a conventional façade
technology. Ideally, the demand for a dynamic building envelope can be fulfilled:
Climate regulation with breathable materials, load transfer with slender optimised
load-bearing systems, comfort with insulation and ventilation, integrated
technology for the user, performance capacity for lighting and shading with adaptive
transparency, design appropriate appearance.
It is important not to understand the dynamic building envelope as a technological
end in itself but rather as an opportunity to elevate the stagnating development
of the building envelope to the next level. Still today, Mike Davies’ vision of a
‘Polyvalent Wall’ in its complexity and slender execution could not yet be turned
into a viable product. However, it does combine all requirements placed on the
building envelope in one concrete formulation.[1]
Chapter 3:
• Which research approaches lead to first experiences with AM technologies in the
building envelope?
In an existing façade system, approaches can be found anywhere where
conventional production methods will not provide sufficient results. Meaning
where conventional production leads to excessive inventory, or where the desired
component performance cannot be fulfilled. Such product-oriented approaches
then lead via modified façade construction with AM to a re-interpretation of the
building envelope.
•
What are the effects of product-oriented project results on a general transfer of the
AM technologies to façade technology?
We can conclude from the specific project that it makes sense to identify and
rework weak system components. The technological development and according
cost reduction for components provided by AM service providers that occurred
during the time to complete this work alone make it apparent that a targeted
application of one-off projects is feasible (see § 3.3.3). Hereby it does not suffice
to merely exchange production methods in order to justify the application of
additive methods. Only an intensive discussion about ‘Funktionales Konstruieren’
(‘functional constructing’) and the according changes in engineering can do justice
to the potential of AM for façade constructions.
AM as an enhancement within a hybrid production chain is the next step toward the
AM Envelope. With the goal being improved façade construction.
181Conclusion
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•
What means of assistance for planners and users of the technologies must be
generated in order to guarantee AM oriented application in the façade?
In order to achieve ‘Design for AM’, planners and users must be provided with
thorough aids for the AM technology. Such aid in form of guidelines provide targetoriented advice for a technically correct handling of AM: Component thicknesses,
orientation within the process chamber, production strategies and many more
support an AM conform design. This can support the economic and resourcefriendly use of AM.
Chapter 4:
• Which developments of the AM technologies for façades are conceivable?
An increasingly thorough discussion about the potential of Additive Fabrication
leads to the demand to develop the AM technologies further. These demands can
be linked to certain time periods:
–– In five years (2020) the technology will have caused changes in existing building
details; AM will be integrated in the production process of extraordinary
architectural projects.
–– In five to ten years (2025) AM will have found its way into the workshops of
façade builders due to improved system technology.
–– In twenty-five to thirty years (2045) the manufacturers of large (façade)
components will use Additive Fabrication with various materials, for hybrid
processes, and to produce dynamic building envelopes and the according
primary structures.
•
182
Which façade applications can result from these developments?
Technology transfer makes it possible to formulate the most diverse ideas and
combinations. Progressing developments in the field of software tools, continuous
CAD and CAM training, and a deeper interconnectedness of hitherto separate
disciplines lead to the comprehensive development of hybrid products. In building
technology, AM applications can still be categorised as follows: semi-finished
product level, element level, component level, and system level. It is only the level
of consequence in formulating the possibilities of AM that will replace the technical
limitations prevailing today in the future. Over the coming years, the development
and application of Additive Fabrication will be further separated into the two
areas ‘professional applications’ (Additive Manufacturing) and ‘Do-it-yourself
applications’ (fabbing). But professional product ideas that a user creates for
personal use can be placed in the latter category as well. Important topics in this
respect are noise and sound, material and recycling as well as climate and comfort.
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•
What effect can an integration of high-tech technologies have on building
technology?
New technologies offer new opportunities in the transformation of the long existing
digital designs into built reality. From an increasing combination of digital design
and digital manufacturing an ever greater precision will be the result. Significantly
improved products can be the result, if the available tools - analogue and digital –
are used effectively. For the building envelope, this means a more user-oriented
and diverse performance, more reliable details, enhanced durability and reliability.
However, with the implementation of new technologies the human factor remains a
crucial part of it.
§ 5.2 Open questions
Some of the unresolved issues on the path to an AM Envelope are:
• the repair of enclosed parts;
• the recycling of high-tech composite materials (‘Design for Disassembly’);
• the replacement or exchange of individual functional parts (How can we repair
structures made of printed glass from Direct Glass Fabrication?);
• the formal and technical enhancements and additions to enclosed structures (How
can we add to a printed building?);
• the readjusting of customized products (How do integral structures respond to
changes that result from modified usage? How truly flexible are perfectly integrated
façade constructions, for example when the user changes?).
Based on today’s knowledge, possible solutions are:
• hand-held units that can be used to repair small defects;
• lasers with different focal lengths that allow melting repair material inside enclosed
parts;
• mono-material parts, where a separation of the different materials for recycling
is unnecessary because the individual part is generated with one homogeneous
material (see § 4.2.1 / Mono Material Recycling Element); after use, these
components can be shredded to granulate and thus fully recycled;
• the use of self-healing materials ensures that the part repairs itself when broken or
worn.
183Conclusion
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As already stated in § 2.6.3 the challenges of further developing AM for façade
technology can be categorised in ‘material’, ‘technology’ and ‘production’:
• Material:
–– the physical properties of AM products: they need to mimic generally accepted
mass products;
–– the materials used under consideration of cost, properties, reworkability and
standardisation;
–– accuracy of the fabricated products in terms of product properties such as
surface finish and dimensional accuracy;
–– programming and fabrication of Functionally Graded Materials (FGM).
• Technology:
–– the possibility of exact reproducibility of identical parts across different
production batches and with different yet technically identical equipment;
–– producible product size: in macro as well as micro range;
–– process speed;
–– achieved resolution with largest possible form, smallest printable detail.
• Production:
–– software access for the user: intuitive processing of 3D data;
–– cost efficiency compared to conventional building products;
–– lower manufacturing cost with AM (equipment cost, maintenance, material cost)
In order to promote further considerations about the use of Additive Fabrication in
façade construction it is necessary to:
• differentiate the use of AM between the different production stages of façade
construction (production, component assembly, assembly on-site, inventory,
performance);
• achieve a deeper understanding of the potential and possible added value that AM
offers: performance, material savings (in production and the system), functional
constructions (component reduction, snap functions, etc.), marketing of the
technology (‘AM inside’), optimised stock-keeping (on-demand production,
just-in-time management), digital designing (freedom of geometry, technically
improved joints, load-transfer optimised building parts, combination of different
functions in fewer component layers;
• understand the potential and let it flow into better constructions aiming for a
dynamic envelope;
• clarify everyone’s expectations concerning the integration of the technologies
into building technology, and to formulate realistic options in terms of realising
customer wishes;
• test and evaluate the potential using a real project on a 1:1 scale, and to draw a
realistic conclusion relevant to the herein stated theses.
(see [2] [3]).
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§ 5.3 Explicit benefits for the façade
Wim Michiels, Executive Vice President of Materialise in Belgium – one of the market
leading service providers in AM – states the following as his personal top 4 reasons to
consider AM:
• added value;
• cost reduction;
• environmental considerations;
• cultural trends.
[4]
Initially, these benefits are explicitly related to the area of manufacturing parts in
plastics. However, at the same time they are the main drivers to further promote the
technology in general. The mentioned added value is related to the freedom of design
and the benefits of the production process. Closely linked are the large possible savings
related to different areas of production (stock keeping, shipping, material requisition,
etc.). Environmental compliancy is a topic often discussed in the AM industry. But
it must be noted that today AM technologies are energy intensive and therefore not
resource friendly. However, when discussing primary energy, the facts that local
production can eliminate long transport distances and that possible fuel savings by
using light weight components particularly in aviation can lead to the conception of AM
as a ‘green’ technology. The last item on the list addresses a change in society. It refers
to the increasing demand for individualised products and personal influence on design
and production that is supported by digital tools.
These arguments for a general growth of the AM technologies can be transferred to and
are also valid for the façade technology: The named benefits are the driving forces for all
economic changes and the adaptation of innovation to a business model.
Additionally, façade-related criteria can be added to the list of reasons above. They
support the application of AM specifically in façade construction:
• independence of scale;
• mass customisation for one-off projects;
• rapid product development = optimisation with every new generation of a product;
every new print allows for enhancements, based on user feedback and user
demands.
185Conclusion
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§ 5.3.1 Nematox II – a realistic approach to system façades?
Related to the actual façade technology of a post-beam system, the following, already
realised benefits can be drawn from the experiences with the Nematox façade node:
• digital deformation and digital fitting;
• cut optimisation;
• diffusion of building technical difficulties related to crossover points (water circuits,
sealing joints);
• digital coding of building parts;
• possible parameterisation of complex geometries across the system;
• diffusion of assembly issues on-site (sealing, accuracy, material waste);
• individual façade geometries, with cutting processes that work for all projects
worked on the system, that means all accessories and tools from the standard
façade system can still be used.
The current version of the ‘Nematox II’ is a prototype. However, following the logical
consequence of the initial developmental steps, it was further developed with smaller
parts of the façade system. The above mentioned advantages are the result of an intensive
discussion about today’s façade construction and production. Combined with Additive
Fabrication they break the path to new shores for the rather conservative building sector.
Even though prototypes clearly show the benefits, these benefits are not necessarily
obvious at the beginning of a planning task. Often, the potential for optimisation
can only be derived from an intensive use of a well-established standard. Potential
only shows when alternative solutions to hitherto unknown disadvantages become
available. Established ways of thinking cannot be changed overnight; new thought
methods must be learned and trained. And they must be based on arguments; and
such arguments are highlighted by a comprehensible physical representation of the
virtual product. This is where we come full circle to the origins of the AM development:
The initial goal was to illustrate ideas that needed to be discussed between designer
and customer, for example colour, shape and feasibility. Today, a prototype made with
such systems serves as the basis for discussion of the performance properties of the
technology itself. Only when a technician can physically touch and thus comprehend a
model will he/she start believing in the technology.
Initial conversations with and feedback from building envelope specialists consistently
show that little explanation is necessary as far as performance goes – even though the
presented node is only the very first step of the development. Possible AM solutions for
failed projects become immediately apparent when viewed on the basis of the newly
gained knowledge. And the initially high cost per item for the prototypes has dropped
so far during the time of this study that this discussion-ending argument from four
years ago is not truly valid anymore. The only thing lacking after the presented ‘proof of
concept’ is a real-life trial in an actual façade project.
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Therefore the Nematox II can be looked upon as a realistic approach to improve system
façades with AM.
§ 5.3.2 AM Envelope as a tangible goal
AM will never replace established production processes but rather complement them
where this seems practical. AM is not the proverbial Swiss-army knife that can resolve
all of today’s façade issues! But it is a tool that might be able to close another link in
the ‘file-to-factory chain’. AM allows us a better, more precise and safer realisation of
today’s predominantly free designs that are based on the algorithms of the available
software. With such extraordinary building projects, the production of neuralgic system
components will become reality in the near future – today, an AM Envelope is close at
hand. Still, ‘printing’ entire buildings lies in the far future; for a long time human skill
and craftsmanship will be needed on the construction site combined with high-tech
tools to translate the designers’ visions into reality.
If AM is to be used as an independent production method, then this method must open
up an independent genre within the building sector that is autarkic and revolutionary;
which consequently means that it is no longer limited to the façade, load-bearing
structure or enclosing envelope. The new production method should, however, be
solely based on AM in order to avoid watering down the large potential of ‘printed
architecture’ by mixing it with conventional methods.
187Conclusion
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§ 5.4 The potential of AM for façade construction
What is the ultimate assessment of the potential of AM technologies for the building
envelope?
Without focussing too much on one particular aspect of the ‘new architecture’, we
must ask who will benefit from this discussion? Is the main underlying goal of these
developments to change or improve design and appearance? Or are they also about
changing the way we build, thus changing building technology?
The discourse who or what will benefit from implementing the new technologies is not
the primary subject matter of this work. But we must have this discussion in order not
to degrade the potential that these technologies offer to an end in itself, which would
mean falling far short of the possibilities. Related to AM, the considerations must
go beyond merely translating free-form designs into built structures – it is all about
changing and improving building technology.
§ 5.4.1 Feasibility
Here fore, the first item on the agenda must be to ensure feasibility; feasibility of
all aspects of production with AM because all areas of AM applications need to be
considered:
• in terms of system technology. Technical limitations must be resolved in the
foreseeable future. However, existing boundaries can only be extended if visionary
approaches are developed that challenge the developers of the technology.
• in terms of an application in façade technology, and ultimately in architecture.
However, a more important criterion is the feasibility of the designs: ‘Clean files’
are needed to realise ‘file-to-factory’ processes, a challenging task. Designs must
reflect the differentness of their realisation in order to justify the applications of
new technologies. Consequently, the change in designing must be preceded by
a different way of thinking about construction, or at least this must flow into a
growing knowledge base.
• in terms of changing the appearance of digital designs. ‘The chicken or the egg?’
Will the designs need to follow the new technology, or will we need to find technical
solutions to realise free-formed designs? Obviously, this study was based on the
latter assumption; there are great opportunities to generate new design methods
based on a thorough understanding of the technologies (‘Digital craftsmanship’).
We are at a crossover point between historically grown engineering – with all of
its advantages and disadvantages – and the digital age that has been promised
for thirty years, and should have made ‘flux capacitors’ (‘Back to the future’)
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and ‘replicators’ (‘Star Trek – The next generation’) common technologies. Even
though AM does not yet allow us to dematerialise organisms in one place and rematerialise them in another, it is possible to send architectural drawings to virtually
any place on earth via the internet where they can be translated from a virtual
to a physical state by means of the technology. This means that our method of
production and handling goods has already changed.
§ 5.4.2 Improvement of building construction
Improved building technology as a main consequence of the potential offered can be
subdivided into several aspects:
the general requirement to improve building technology is related to its functionality
and therefore the functionality of the building components. The overall technology
can only be optimised if the sub-aspects are optimised. AM offers the opportunity
to increase functionality (ease of assembly, component simplicity, system-wide
functionality, flexibility). The functions of the individual elements can, in turn, be
improved by the new way of constructing (integration, multi-functionality)
• in addition there is the connection of different parts of the digital production
chain (file-to-factory). The challenge here is to improve the processes and the
interconnectivity between the individual steps of the digital development and
digital production. AM is an opportunity to fulfil this demand if it is used as one part
of the process.
§ 5.4.3 Requirements for the future handling of AM
The potential of AM for façade construction is great if the necessary steps are taken to
employ it sensibly. Requirements on how to handle the AM technologies from here on
out can be derived from the findings:
• certification / standardisation of the methods;
• intuitive application of the technology;
• easier file generation;
• testing in the façade industry / building industry;
• demand for building-relevant materials;
• interdisciplinary teams for further integration into façade production;
• technology transfer to hybrid production methods.
189Conclusion
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§ 5.4.4 Quality standards
No quality standards or norms have yet been established for products manufactured
with AM technologies. A catalogue of traceable criteria must be developed so that
products can be compared to each other and to conventional mass products. A rating
system for the manufactured parts, quality standards for the available methods, and
materials as well as quality control for the individual methods are key requirements
when developing a mutually accepted manufacturing method. The methods must be
certified, i.e. authorised by building law in order to be used in façade technology. Thus,
individual AM methods can obtain official technical approval based on a specification
of the targeted material parameters.
In order to allow for wider spread use, the software should be even more intuitive.
Similarly to Building Integrated Modelling (BIM), the user must be able to set
parameters while generating the file that defines the realisable properties of the AM
product and tailor it to a particular AM method. Expert knowledge is still needed for 3D
modelling and parametric designing; however, after the next generation change this
will no longer be considered a boundary.
Integrating AM into a façade system must be tested under realistic conditions. Only
the experiences gained during a defined building project will yield the necessary
knowledge.
Considering such testing, it is obvious that other materials than metals come into
question as well if they exhibit the properties necessary for use in the façade. In this
context, the often cited comparison between the innovative automotive industry and
the building industry is very poor: Because, due to very different maintenance intervals
and very different liability and safety requirements the often advocated demand to
deal with new materials more courageously cannot be directly compared for the two
industry sectors. On average, a car is checked by a technical inspection agency every one
or two years, and often undergoes even more inspections between these intervals. After
assembly, a façade, on the other hand, must function for thirty years and more without
the possibility to conduct such inspections in an economically reasonable manner.
Against this background the building industry’s reluctance to test new materials in
a real project is understandable. We can only plan reliably with AM products if the
methods are certified as reliable production methods.
Therefore, an application of Additive Fabrication in façade technology must clearly
be targeted toward complementing conventional production methods, not replacing
them. A hybrid integration of various production methods leads to the desired – and
economically reasonable – solutions. AM is one building block of a whole.
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§ 5.4.5 Advancements
To finalize this dissertation, advancements need to be clearly stated, that are to be
expected from Additive Manufacturing for building envelopes:
• a change of the production methods corresponding to the digital revolution - now
also in the physical world;
• a change of engineering toward ‘Funktionales Konstruieren’ (functional
constructing) – turning the known engineering upside down;
• today’s protagonists in the building industry to turn toward ‘Digital Craftsmanship’;
• technical and formative added value;
• greater freedom in design and function integration.
Because we are used to think subtractive rather than functionally it is difficult to
identify suitable AM applications for the building technology. Still, the general
discussion and growing awareness resulting from the described benefits of additive
methods will generate many new construction principles. This development is still
in the beginning stage; but AM offers the potential to lastingly change design and
manufacturing methods.
“The goal is no longer to design according to production method, but to produce
according to design idea.”7 [5]
References chapter 5
[1]
Knaack, K., Bilow, Auer, Façades. Principles of Construction. 2007, Basel: Birkhäuser Verlag AG.
[2]
Strauss, H., AM Façades - Influence of additive processes on the development of façade constructions. 2010,
[3]
Strauss, H., Funktionales Konstruieren - Einfluss additiver Verfahren auf Baukonstruktion und Architektur, in
Hochschule OWL - University of Applied Sciences: Detmold. p. 83.
Fachbereich 1 - Lehrgebiet Konstruieren und Entwerfen. 2008, Hochschule OWL: Detmold. p. 136.
[4]
Michiels, W. The Evolution of the Additive Manufacturing Market. in Materialise World Conference. 2012.
[5]
Honsel, G., Drucken in 3D, in Technology Review - Das M.I.T.-Magazin für Innovation. 2006, Heise Zeitschriften
Leuven, Belgium: Materialise.
Verlag: Hannover.
7
Citation: Wilhelm Meiners, Fraunhofer Institut für Lasertechnik, Germany
191Conclusion
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6 Summary
§ 6.1 Summary
This dissertation shows the potential of Additive Manufacturing (AM) for the
development of building envelopes: AM will change the way of designing facades,
how we engineer and produce them. To achieve today’s demands from those future
envelopes, we have to find new solutions.
New technologies offer one possible way to do so. They open new approaches in
designing, producing and processing building construction and facades. Finding the
one capable of having big impact is difficult – Additive Manufacturing is one possible
answer.
The term ‘AM Envelope’ (Additive Manufacturing Envelope) describes the transfer of
this technology to the building envelope. Additive Fabrication is a building block that
aids in developing the building envelope from a mere space enclosure to a dynamic
building envelope.
First beginnings of AM facade construction show up when dealing with relevant aspects
like material consumption, mounting or part’s performance.
From those starting points several parts of an existing post-and-beam façade system
were optimized, aiming toward the implementation of AM into the production chain.
Enhancements on all different levels of production were achieved: storing, producing,
mounting and performance.
AM offers the opportunity to manufacture facades ‘just in time’. It is no longer
necessary to store or produce large numbers of parts in advance. Initial investment for
tooling can be avoided, as design improvements can be realized within the dataset of
the AM part. AM is based on ‘tool-less’ production, all parts can be further developed
with every new generation.
Producing tool-less also allows for new shapes and functional parts in small batch
sizes – down to batch size one. The parts performance can be re-interpreted based
on the demands within the system, not based on the limitations of conventional
manufacturing. AM offers new ways of materializing the physical part around its
function. It leads toward customized and enhanced performance.
193Summary
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Advancements can for example be achieved in the semi-finished goods: more effective
glueing of window frames can be supported by Snap-On fittings. Solving the most
critical part of a free-form structure and allowing for a smart combination with the
approved standards has a great potential, as well.
Next to those product oriented approaches toward future envelopes, this thesis
provides the basic knowledge about AM technologies and AM materials.
The basic principle of AM opens a fascinating new world of engineering, no matter what
applications can be found: to ‘design for function’ rather to ‘design for production’
turns our way of engineering of the last century upside down. A collection of AM
applications therefore offers the outlook to our (built) future in combination with the
acquired knowledge.
AM will never replace established production processes but rather complement them
where this seems practical. AM is not the proverbial Swiss-army knife that can resolve
all of today’s façade issues! But it is a tool that might be able to close another link in
the ‘file-to-factory chain’. AM allows us a better, more precise and safer realization of
today’s predominantly free designs that are based on the algorithms of the available
software. With such extraordinary building projects, the digital production of neuralgic
system components will become reality in the near future – today, an AM Envelope
is close at hand. Still, ‘printing’ entire buildings lies in the far future; for a long time
human skill and craftsmanship will be needed on the construction site combined with
high-tech tools to translate the designers’ visions into reality. AM Envelope is one
possible result of this!
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§ 6.2 Samenvatting
Dit proefschrift toont de potentie aan van Additive Manufacturing (AM) voor de
ontwikkeling van gevels: AM zal van gevels de wijze van ontwerpen en ook de wijze van
construeren en produceren veranderen.
Om te voldoen aan de eisen van de toekomstige uitwendige scheidingsconstructie
moeten er nieuwe wegen ingeslagen worden. Nieuwe technologieën bieden daarvoor
de mogelijkheid. Ze openen nieuwe wegen voor het ontwerpen en produceren en voor
nieuwe implementatiestrategieën.
De juiste technologie te vinden voor de bouwenvelop is een uitdaging – AM is hierop
een mogelijk antwoord.
De term AM Envelope (Additive Manufacturing Envelope) beschrijft het overbrengen
van deze technologie naar de uitwendige scheidingsconstructie van een gebouw. De
additieve werkwijze is een bouwsteen, welke helpt bij de ontwikkeling van de gevel van
een louter fysieke barrière naar een meer dynamische bouwenvelop.
De eerste toepassingen van AM in de geveltechniek, laten de mogelijkheden
zien van relevante aspecten als materiaalgebruik en montage, maar ook de
prestatiemogelijkheden bij individuele bouwdelen.
Vanuit deze uitgangspunten werden verschillende onderdelen van een bestaand “stijlen regelwerk” gevelsysteem geoptimaliseerd, met als doel de productiemethoden van
AM te testen, te optimaliseren en te verbeteren.
Op allerlei productieniveaus werden verbeteringen bereikt: opslaan, produceren,
monteren en kwaliteit. AM biedt de mogelijkheid om gevels “just in time” te
vervaardigen. Het is niet langer nodig om grote aantallen vooraf te produceren of
in voorraad te hebben. Initiële investeringen van gereedschap zijn niet meer nodig,
verbeteringen van het ontwerp kunnen worden gerealiseerd via de dataset van het AM
onderdeel. AM is gebaseerd op productie zonder gereedschap, waarbij alle onderdelen
in de toekomst verder doorontwikkeld en aangepast kunnen worden.
Gereedschapsloze productie maakt de weg vrij voor nieuwe vormen en functionele
bouwonderdelen in kleine aantallen. De deelprestaties van onderdelen kunnen
geïnterpreteerd worden op basis van de vragen binnen het systeem en niet gebaseerd
op de beperkingen van conventionele productiemethoden. AM biedt nieuwe wegen
van materialisatie van speelruimte tot individuele functionaliteit en een verbeterde
prestatie.
Het leidt tot nieuwe mogelijkheden met betrekking tot klantvriendelijkheid en
verbeterde prestatie.
Verbeteringen kunnen bij voorbeeld gebruikt worden bij het optimaliseren van
halffabricaten: effectievere verlijming van kozijnprofielen met behulp van klikprofielen.
Het oplossen van het meest kritische onderdeel van een vrije vorm structuur en de
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mogelijkheid van een slimme combinatie met goedgekeurde normen, geeft grote
mogelijkheden.
Naast deze productgerichte aanpak in de richting van de toekomstige verbeterde
bouwenvelop levert dit proefschrift de basiskennis over AM technologieën en AM
materialen.
Het basisprincipe van AM opent een fascinerende nieuwe technische wereld, ongeacht
welke toepassingen er bedacht worden: Het “ontwerpen voor de functie” in plaats van
“het ontwerpen voor de productie” zet onze wijze van engineering van de afgelopen
eeuw op zijn kop. Een verzameling van AM toepassingen geeft daarom, in combinatie
met de verworven kennis, een blik naar onze (gebouwde) toekomst.
AM zal nooit gevestigde productieprocessen vervangen, maar aanvullen daar waar
het zinvol is. AM is niet het spreekwoordelijke Zwitserse zakmes, dat alle huidige
gevelproblemen kan oplossen! Maar het is een instrument dat misschien in staat
is een slimme link te maken in de productieketen. AM stelt ons in staat om veel
voorkomende vrije ontwerpen beter, preciezer en veiliger te verbeteren en uit te voeren,
gebaseerd op de algoritmen van de beschikbare software.
Met dergelijke buitengewone bouwprojecten, zal de digitale productie van neuralgische
systeemcomponenten in de nabije toekomst – nu – werkelijkheid worden, een AM
Envelope is dichtbij. Toch ligt het printen van gehele gebouwen in de verre toekomst;
nog lang zal menselijke vaardigheid en vakmanschap, gecombineerd met high-tech
gereedschap nodig zijn op de bouwplaats om de visie van de ontwerper tot realiteit te
maken. AM Envelope is hier een mogelijk resultaat van!
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§ 6.3 Zusammenfassung
In dieser Dissertation wird das Potential der additiven Verfahren für die Entwicklung
von Fassadenkonstruktionen aufgezeigt: die Additiven Verfahren (Additive
Manufacturing - AM) verändern die Art und Weise, wie wir Gebäudehüllen entwerfen,
wie wir sie konstruieren und produzieren.
Um den heutigen Anforderungen an die Gebäudehülle gerecht werden zu können,
müssen neue Wege beschritten werden. Neue Technologien bieten einen Ansatz
zur Entwicklung neuer Herangehensweisen, neuer Produktionsweisen und neuer
Umsetzungsstrategien. Die richtige Technologie für die Verbesserung der Gebäudehülle
zu finden, ist eine Herausforderung – AM ist eine mögliche Lösung auf dem Weg.
Der Begriff „AM Envelope“ (Additive Manufacturing Envelope) beschreibt den Transfer
dieser Technologie in die Gebäudehülle. Die additiven Verfahren stellen einen Baustein
dar, der die Weiterentwicklung der Gebäudehülle vom reinen Raumabschluss hin zu
einer dynamischen Gebäudehülle unterstützt.
Erste Ansätze zur Anwendung von AM in der Fassadentechnik zeigen sich bei der
Betrachtung der relevanten Aspekte wie Materialverbrauch, Montage, aber auch
bei der Leistung einzelner Bauteile. Über diese Aspekte wurden erste Bauteile aus
einem bestehenden Pfosten-Riegel-System ausgewählt, und mit dem Ziel, AM als
Produktionsverfahren zu erproben, optimiert und verbessert.
Verbesserungen konnten hierbei in allen Phasen der Herstellung einer solchen Fassade
erzielt werden.
Die additiven Verfahren ermöglichen ein Just-Intime-Management im
Produktionsablauf. Lagerhaltung und Vorproduktion großer Produktmargen entfallen.
Ebenfalls können Investitionskosten zum Beispiel für den Werkzeugbau eingespart
werden, wenn neue oder veränderte Bausteine im System benötigt werden. Mit AM
wird werkzuglos gefertigt. Alle notwendigen Informationen werden digital in einen
Datensatz implementiert und führen somit zu Bauteilen, die stetig weiterentwickelt
und angepasst werden können.
Die werkzeuglose Fertigung ermöglicht neue Geometrien und funktionale
Bauteile in kleinen Stückzahlen. Dies eröffnet bei der Herstellung und Montage
der Fassadensysteme neue Möglichkeiten. Ausformungen einzelner Teile eines
Systembausteins werden nicht mehr von den konventionellen Herstellungsverfahren
bestimmt, sondern können mit AM neu interpretiert werden. Die Herangehensweise bei
der Umsetzung einer technischen Anforderung wird in Zukunft von der Funktion gelöst,
und nicht mehr durch die Herstellbarkeit limitiert. AM eröffnet also bei Herstellung und
Montage neue Spielräume für individualisierte Funktionalität und verbesserte Leistung.
Eine verbesserte Leistung kann sich zum Beispiel bei der Optimierung von Halbzeugen
zeigen. Leistungsstärkere Komponenten können hierbei zu einer Verbesserung
des Endprodukts führen – beispielsweise bei der schnelleren Verklebung von
Rahmenprofilen durch selbst stützende Schnapp-Mechanismen. Eine andere
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Leistungssteigerung kann bei der Lösung von neuralgischen Problempunkten erfolgen.
Werden beispielsweise Verformungen der Tragstruktur ausschließlich an wenigen,
aber entscheidenden Punkten gelöst, kann der verbleibende Anteil der Konstruktion
weiterhin mit den bekannten Standards abgedeckt werden.
Neben diesen stark produktorientierten Lösungsansätzen für die verbesserte
Gebäudehülle vermittelt die Arbeit auch das Hintergrundwissen zu den AM
Technologien und zu den verwendeten Materialien.
Das grundsätzliche Prinzip ‚AM‘ fasziniert unabhängig von einer konkreten
Anwendung: das Funktionale Konstruieren stellt das Ingenieurswissen der
vergangenen hundert Jahre auf den Kopf.
Eine Sammlung von Anwendungsideen bietet hierzu die Möglichkeit das neue Wissen
zu den Technologien mit einem Blick auf unsere (gebaute) Zukunft zu verbinden.
Nie wird AM die etablierten Produktionsabläufe ganz ersetzten, sondern sie immer
nur dort ergänzen, wo es sinnvoll ist. AM ist keine Allzweckwaffe, die alle heutigen
Probleme in der Fassade lösen kann! Aber AM ist das Werkzeug, welches es schaffen
kann ein weiteres Glied in der Produktionskette zu schließen. Mit AM wird es möglich,
die heute zunehmend freieren Entwürfe besser, genauer und sicherer umzusetzen.
Die Gestaltung ergibt sich dabei aus den Algorithmen der verfügbaren Software.
Und auch bei der Umsetzung dieser Bauaufgaben lässt sich die Herstellung der
neuralgischen Systemkomponenten mit den digitalen Werkzeugen schon in der nahen
Zukunft ablesen - ein AM-Envelope ist heute in greifbarer Nähe. Trotzdem werden
zunächst keine ganzen Gebäude „gedruckt“ und es wird noch für eine lange Zeit das
menschliche Geschick auf der Baustelle gefordert sein, welches es ermöglicht mit den
High-Tech Werkzeugen die Visionen der Planer umzusetzen. Gedruckte Gebäudehüllen
sind ein mögliches Ergebnis davon!
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Part 2
Appendices
201Summary
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A I Additional information AM
AM history
The actual motivation behind the development of Additive Fabrication – that means
the possibility of creating physical parts from virtual data – is shrouded by various
myths.
Figure 86
Left: Astronaut Buzz Aldrin, lunar module pilot, walks on the surface of the Moon near the leg of the Lunar Module
(LM) “Eagle” during the Apollo 11 extravehicular activity (EVA). Astronaut Neil A. Armstrong, commander, took
this photograph with a 70mm lunar surface camera.
Right: Astronaut Eugene A. Cernan, Apollo 17 mission commander, makes a short checkout of the Lunar Roving
Vehicle during the early part of the first Apollo 17 extravehicular activity (EVA-1) at the Taurus-Littrow landing
site. This view of the “stripped down” Rover is prior to loadup. This photograph was taken by Geologist-Astronaut
Harrison H. Schmitt, Lunar Module pilot. The mountain in the right background is the East end of South Massif.
Imagery courtesy by NASA.
One states that the fundamental idea to develop additive methods came from NASA.
According to unverified sources, NASA tried to give its astronauts digital building
plans for spare parts and other items to take on their travels to new planets. Instead of
physical parts only digital building plans as well as a ‘printer’ were to be taken along to
save space and weight.[1] [2]
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This thought was taken up and interpreted by other inventors. An approach by Prof.
Bherokh Khosnevis was aimed at creating housing on the moon with ContourCrafting
(see § 2.2.4.1). The goal of the approach is to exploit locally available materials – in
this case lunar dust – to generate structures with layering methods. The underlying
thought is the same: Digital building plans contain all necessary information about
performance and manufacturing strategy, and an AM system materialises the parts
with little hardware requirements. Physical parts are generated from 3D data with
regional materials and a targeted use of the technology.[3] [4]
Figure 87
ContourCrafting: Printed model of a lunar cupola structure (left); internal structures of cupola with printer head
(right). Imagery courtesy by B. Khoshnevis.
Build-up welding and additive methods have also been applied for direct
manufacturing of metal parts for the military. The U.S. Army employs so-called ‘Mobile
Parts Hospitals’, which are used to repair defect vehicle parts or to fabricate spare parts
with CAD data or reverse engineering directly in the operational area. Repair times for
emergency and other vehicles are thus significantly reduced. The mobile workshop is
setup in a 20 foot container, and can be shipped to the operational area just like any
other gear by air, by sea or by land. Due to the limited space available, only very effective
and versatile tools are used on board. This requires that the production data is available
as 3D data records (point clouds und scanner files), as well as the possibility to create
various shapes with a limited number of tools. In addition to the additive methods,
high-speed milling machines are used for this purpose.
[5] [6]
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AM technologies in detail
Characteristic tables of AM processes – plastics
The profiles of the individual methods provide a detailed overview of the method, the
manufacturers and a link to respective web pages.
Laser Sintering
AM process
(Selective) Laser Sintering
Abbreviation
LS (SLS)
Main-Application
Prototyping,
Manufacturing of end use parts,
Tool making (mounting devices, positioning devices)
Material
Plastics: Polyamide, PEEK, Alumide
Other: Ceramics
Invented by
DTM, USA
Year
1992
Manufacturer
EOS
3D Systems
Building Chamber (mm)
700x380x580
550x550x750
Material
Polyamide, Peek
Polyamide
System
EOSINT P 730
sPro 230
URL
http://www.eos.info/
http://www.dimensionprinting.com
Further information
The process heat required for this method means that the models need to cool before they can
be removed from the system. According to EOS, Germany, the duration of the cooling phase
equals the duration of the actual sintering process.
If some thermoplastics are heated, the structure can change which in turn can influence the
material properties of the finished model. Therefore, if used powder is reused, the manufacturers specify the required percentage of new powder to be added to the process.
LS is also employed to generate models made from other powders (Alumide) and ceramic
casting moulds. For both applications the raw powder is encased in a polymer coating. The
sintering process causes the polymer to melt which in turn allows the raw powder to melt. The
properties of parts made of Alumide are closer related to those of polyamide parts than those
made of aluminium; the results are not metal parts!
With ceramics, the results are so-called green shapes (unfinished models) that are cured
in a subsequent process. The polymer is burnt out and the porous structures are filled with
infiltration material.
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Stereo Lithography Apparatus
AM process
Stereo Lithography Apparatus
Abbreviation
SLA (sometimes STL)
Main-Application
Prototyping
Material
light curing resins (Photopolymers):
Invented by
3D Systems, USA
Year
1987
Manufacturer
3D Systems
Materialise
Building Chamber (mm)
650x750x550
2100x700x800
Material
Epoxy resins, acrylic resins
Epoxy resins, acrylic resins
System
iPro 9000 SLA Center
Mammoth
URL
http://www.3dsystems.com
http://www.materialise.com/
Further information
Stereolithography was the forerunner to AM. Compared to later developments it still has an
advantage in terms of accuracy and resolution. The type of resin used varies greatly; each
­manufacturer offers optimised material compounds for a particular system. Professional
systems are relatively large. Therefore, they are not yet suited for office use. A SLA system
requires several peripheral devices such as a special chamber to remove support ­structures,
for example, a pre-heater for the resin cartridges, a quick mount module for a second process
chamber, and a post-process curing chamber. Compared to other equipment for plastic part
manufacturing, these systems are expensive. The resins used are not long-term UV or humidity
resistant. Therefore, their use in the building sector is questionable.
Chuck Hull
Fused Deposition Modelling
AM process
Fused Deposition Modelling
Abbreviation
FDM
Main-Application
Prototyping,
Tool making (mounting devices, positioning devices)
Material
Plastics: ABS, Nylon, Wax (casting cores)
Invented by
Stratasys, USA
Year
1991
Manufacturer
Stratasys
Dimension
Building Chamber (mm)
914x610x910
254x254x305
Material
ABS, ABSplus
ABS, ABSplus
System
Fortus 900mc
Elite
URL
http://www.stratasys.com
http://www.dimensionprinting.com
Further information
FDM is distributed via various licence holders: Alphacam, Fortus, Hewlett-Packard, Dimension, etc.
An extrusion nozzle processes the strings of material at approximately 280°C. Different nozzle
diameters are available, and the melting temperature can be accurately controlled on the nozzle.
Coloured materials can be used. However; since each material must be placed into the system
individually, colour gradients or colour mixes are not possible.
FDM can also be used to make melt-out models for casting. In general, FDM can be used with
all meltable materials (see chapter 4.2: ‘Direct Glass Fabrication’).
FDM systems are suitable for office use and are relatively quiet.
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3D Printing
AM process
3D Printing
Abbreviation
3DP
Main-Application
Prototyping,
Manufacturing (artefacts of art pieces),
Tool making (casting cores)
Material
Other: starch, gypsum, casting sand, PMMA
Invented by
Massachusetts Institute of Technology, USA
Year
mid 1990’s
Manufacturer
Z-Corporation
3D Systems
Voxeljet
Building Chamber (mm)
254x381x203
550x393x300
4000 x 2000 x 1000
Material
Gypsum
Gypsum
casting sand, PMMA
System
Zprinter 650
sPro 230
VX4000
URL
http://www.zcorp.com
http://www.3dsystems.com
http://www.voxeljet.de
Further information
The infiltration with epoxy resin or instant adhesive can be done by dipping, coating or soaking.
Due to the lower density of the materials used, the durability of 3DP models is lower than that
of SLA or SLS models, but is comparable to that of brittle plastics. Final stability largely depends on the geometry and property of the individual model. Filigree parts will remain fragile
whereas larger, more complex parts are more robust.
The colour spectrum corresponds to a 24 bit true colour rendition. However, since a binding
agent is used instead of a black colour cartridge, true shades of black cannot be rendered. Different from the actual CMYK palette, all colours are created using the three colours available.
Full colour intensity only becomes visible after infiltration.
3DP models are also used as intermediate products for further use in printing block fabrication and moulding technology. Thus, German system manufacturer Voxeljet has established
their systems in the field of supplies for casting core manufacturing. The powder material for
this process consists of silica sand bonded with an inorganic binder. The results are fragile
casting cores that are used to fabricate metal casting moulds. Foundries have recognised
the 3DP method as an opportunity to generate geometrically demanding parts directly from
CAD data. All of the necessary supply and exhaust lines, lifting and fixing points are directly
integrated in the CAD model. Particularly with Voxeljet, industry demands have caused the
company to drastically enlarge the process chambers of their systems. Systems with process
chambers as large as 4 x 2 x 1 metre have been built to produce casting cores for large ship’s
engines and body parts! In order to be able to handle such process chamber dimensions,
Voxeljet has chosen a combination of the 3D Printing and the Inkjet technologies. On their
system ‘VX4000’, 26,650 serially connected print nozzles deposit a 1.12m wide bed of powder with an inorganic binder. (see chapter 2.4) Voxeljet’s systems feature a layer thickness
resolution of 0.08 – 0.15 mm.
Advanced technological developments allow considering new areas of application, for
example in the field of manufacturing replicas. Herewith, deceivingly real replications of
works of art can be created. A 3D scanner first collects the precise dimensions of the item,
then transforms the data into a print-ready file, and finally creates it based on all necessary information about chromaticity and surface structure. This application can be used by
museums and galleries to preserve original works of art, or to make others that are not fit for
display, accessible to the public.
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InkJet
AM process
InkJet
Abbreviation
PolyJet (Objet, Israel)
MultiJet (3D Systems, USA)
Main-Application
Prototyping, Manufacturing
Manufacturing of end use parts (design parts), Tool making (mounting devices, positioning
devices)
Material
Plastics: Light-curing, viscous plastics;
Invented by
PolyJet: Objet Geometries, Israel
Year
Mid 1990ies
Manufacturer
Objet
3D Systems
Building Chamber (mm)
500x400x200
550x393x300
Material
Acrylate
Acrylate
System
Connex500
ProJet5000
URL
http://de.objet.info
http://www.3dsystems.com
Further information
Great progress has been made in the area of materials. With the PolyJet technology it is possible to mix numerous gradients of the two original materials directly onto the process platform,
using so-called ‘digital’ materials. Because the material is deposited droplet by droplet, the
base materials mix at the predefined ratio when hitting the building platform. Here fore, the
digital model of an object contains the information about the mix ratio that is predetermined
in percentaged gradation. Thus, different areas of the part can feature different material
properties. We know this from handles with hard as well as soft parts, for example, or remote
controls with a hard casing but soft buttons. This is of great advantage for realistic prototype
production (for example for flexible joints, rubber soles, springs a. o.). Currently, the systems
support up to six pre-programmed material mixes made up of two base materials each.
Further development depends on improving the software, not the system technology. It is not
yet possible to program a 3D model such that different materials are allocated within a part
(solid). Manufacturability of digital materials marks a significant step in material and system
development, and opens up a development of true seamless graded materials (FGM’s) on the
basis of an available AM process. Even though it is not yet possible to print the materials in a
true gradient, meaning with seamless transition, current technical feasibility already points
toward the next step: programming true seamless gradient materials (see chapter 2.4).
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Characteristic tables of AM processes - metals
Selective Laser Melting
AM process
Selective
Abbreviation
SLM
Main-Application
Rapid Tooling: production parts,
Manufacturing: end use parts (aerospace, automotive),
Prototyping
Material
Metal: all kinds of metal powders; metals alloys
Invented by
MCP. Germany
Year
2004
Manufacturer
SLM Solutions GmbH
Renishaw
Realizer GmbH
Building Chamber (mm)
250x250x215
250x250x215
250x250x215
Material
Metal alloys
Metal alloys
Metal alloys
System
SLM 250
SLM 250
SLM 250
URL
http://www.slm-solutions.com www.renishaw.com
Further information
The method was developed by MCP (later MTT Group and SLM Solutions, today Renishaw and
SLM Group.). It derives from a research initiative by Fraunhofer Institut, the company Trumpf
and the developers Fockele and Schwartz.
Following several restructuring efforts within the company (MCP), the later group of companies
(MTT), and the separation of the developers, there are three sales channels for the SLM technology today.
Research and development is still done in Germany. SLM Solutions GmbH is a direct successor
of the original MCP GmbH.
There are no requirements in terms of the material powder to be used. The SLM system is an
open system that allows the user to test and modify different materials.
Since its beginnings the SLM system featured an integrated QM system that generates a
detailed protocol with processing parameters for each job. What other system suppliers now
advertise as a new development is a long-time established technology with SLM.
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www.realizer.com
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Laser Engineered Net Shaping
AM process
Laser Engineered Net Shaping
Abbreviation
LENS / DMDS
Main-Application
Rapid Tooling: deep-repair applications for engine parts,
Rapid Manufacturing: semi-finished parts (aerospace, power plants)
Material
Metal: all kinds of metal powders; metals alloys
Invented by
Sandia National Laboratories, USA
Year
1994 - 1997
Manufacturer
Sandia National Laboratories
Building Chamber (mm)
170 x 220 x 145
Material
Metal alloys
URL
http://www.sandia.gov
Further information
Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a
wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s
National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and
Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and
­environmental technologies, and economic competitiveness.
Optomec offers ready-to-use systems in various configurations as well as a research system.
The latter can be used to test and evaluate different materials.
LaserCusing
AM process
LaserCusing
Main-Application
Rapid Tooling: production parts,
Manufacturing: functional parts,
Prototyping
Material
Metal: all kinds of metal powders; metals alloys
Invented by
Concept Laser GmbH, Germany
Year
2000
Manufacturer
Concept Laser
Building Chamber (mm)
300x350x300
Material
Metal alloys
System
M3 linear
URL
www.concept-laser.de
Further information
One application for this method is Rapid Tooling; tools can be made with contour conform
cooling channels. Examples of such tools are casting inserts for spray tools, cast iron tools, and
prototype tools.
Another application are finished products made of steel and products for the medical industry.
The term ‘Cusing’ is derived from the first letter of the company name Concept Laser and part
of the word fusing.
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Electron Beam Melting
AM process
Electron Beam Melting
Abbreviation
EBM
Main-Application
Rapid Tooling: production parts,
Manufacturing: medical implants (dental, chirurgical), jewellery
Material
Metal: all kinds of metal powders; metals alloys
Invented by
Arcam, Sveden
Year
1997
Manufacturer
Arcam
Building Chamber (mm)
200x200x350
300 (diameter) x200 (height)
Material
Metal alloys
Metal alloys
System
A2
A2
URL
http://www.arcam.com
Further information
Arcam introduced its own development with a particular jet melting method. By using an
electron beam instead of a laser, this technology offers advantages in terms of maintenance
and energy consumption.
In order to increase the processing speed, Arcam developed a ‘Multibeam System’, which can
trace the entire building plan more quickly.
Over the past years, Arcam did not work on enlarging the process chamber but rather on fine
tuning the technology. Their target market segments are medical applications and jewellery
making. These applications do not require large process chambers.
Direct Metal Laser Sintering
AM process
Direct Metal Laser Sintering
Abbreviation
DMLS
Main-Application
Rapid Tooling: production parts,
Manufacturing: medical implants (dental, chirurgical), jewellery
Material
Metal: all kinds of metal powders; metals alloys
Invented by
EOS, Germany
Year
1994 (LS for plastics)
Manufacturer
EOS
Building Chamber (mm)
250x250x215
Material
Metal alloys
System
EOSINT M 270
URL
http://www.eos.info
Further information
EOS developed the first marketable AM system to process metals. It is sold since 1994.
In the field of laser sintering, EOS is the global market leader. The development of DMLS was
further driven on this background and with the existing machines. Special developments serve
niche markets such as the jewellery industry (gold), micro applications in the field of laser
sintering or special applications for high-tech plastics (PEEK).
EOS only permits their own material mixes to be used on their systems. The warranty policies
prohibit testing of new materials or using cheaper industry standard powders.
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Electron Beam Free Form Fabrication
AM process
Direct Manufacturing / Electron Beam Free Form Fabrication
Abbreviation
DM / EBF³
Main-Application
Rapid Tooling: production parts, functional prototypes;
Material
Metal: titanium, stainless steel, nickel and refractory alloys
Invented by
Sciaky, USA
Manufacturer
Sciaky, USA
Building Chamber (mm)
4978x2286x1778 (Moving Gun EB)
Material
Metal alloys
System
VX.4
URL
http://www.sciaky.com
Further information
First invented by NASA engineers, EBF³ is now turned into DM and is being sold commercially
by Sciaky, USA.
Advantages of AM: Compared to milled shapes, material cost can be lowered, manufacturing
cost and time expenditure for moulding tools are eliminated, small batch sizes down to 1 piece
are possible, geometries can be optimised, and hybrid applications with standard methods are
sensible.
Direct Laser Additive Manufacturing
AM process
Construction laser additive directe - Direct Laser Additive Manufacturing
Abbreviation
CLAD
Main-Application
Rapid Tooling: production parts,
Manufacturing: functional parts
Material
Metal: all kinds of metal powders; metals alloys
Invented by
IREPA-Laser, France
Year
2009
Manufacturer
EasyCLAD Systems
Building Chamber (mm)
1500x800x800
Material
Metal alloys
System
Magic LF6000
URL
http://www.easyclad.com
http://www.irepa-laser.com
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Direct Metal Deposition
AM process
Direct Metal Deposition
Abbreviation
DMD
Main-Application
Rapid Tooling: repair of metal parts;
Manufacturing: depositing complex metal alloy powders on massive tool/die components for
manufacture and repair in industry applications
Material
Metal: all kinds of metal powders; metals alloys
Invented by
POM Group, USA
Year
1996, 2000 (commercial version)
Manufacturer
POM Group
POM Group
Building Chamber (mm)
673x749x474 (3D axis)
3.2m x 3.665m x 360˚ (robot arm)
Material
Metal alloys
Metal alloys
System
DMD505D
66R
URL
http://www.pomgroup.com/
Further information
The basic system called “Laser Cladding” was developd at the University of Illinois, later at
the University of Michigan by Dr. Jyoti Mazumder. What first started as a 2D machining, later
turned into a 3D free form application.
DMD was first commercially available in 2000, and still Is distributed by POM. POM was
founded in 1998.
The Robotic DMD® system offers a work envelope of 1.955m x 2.14m x 330˚ (Model 44R) or
3.2m x 3.665m x 360˚ (Model 66R). Whereby a DMD head is mounted on a 6-axis industrial
robotarm.
DMD is a direct modification of contract laser welding with AM technologies. In addition to
systems that process material powders, there are those working with material in wire form that
is supplied to the melting pool automatically.
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Dr. Jyoti Mazumder
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Characteristic tables of other AM methods
There are other methods than the AM technologies described in the main part of this
dissertation; however, they have no relevance for façade technology. For the sake
of completeness they are listed and described here – they complement the overall
picture of the diversity of the AM methods. Under consideration of the requirements of
adapting the technologies for an application in the façade technology, as described in
the main part, they do offer inspiration for further development.
High Viscous Material Ink Jetting
AM process
High Viscous Inkjetting
Abbreviation
Main-Application
None: aims toward end use parts with multi-materials
Material
plastics: high viscous, UV curing polymers, can be filled with secondary material
Invented by
TNO, Netherlands
Year
2007
Manufacturer
TNO
Building Chamber (mm)
254x381x203
Material
High viscous polymers
System
Beta system
URL
http://www.tno.nl
Further information
The Dutch research institute TNO creates beta systems for path-breaking technologies. These
are then brought to marketability with an industry partner to earn back the investment.
The process mentioned here, which enables various materials to be printed simultaneously is
quite unique. Currently, three print heads are being used. More may be added in the future.
Currently, no other developments of this technology exist other than the beta system!
A notable development in the field of inkjet technologies (see PolyJet) was conducted
by the group ‘Additive Manufacturing’ of the department ‘High Tech Systems and
Materials’ at the Dutch research institute TNO. The beta system for High Viscous Ink
Jetting makes it possible to create true material gradients.
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Figure 88
Gradient spiral prototype with fading materials, produced with High Viscous Inkjetting technology by TNO.
Special software is used to save the geometry and material properties of the desired
3D part in a GIFF file (Graphics Interchange File Format). These building plans reflect
the material distribution with a point-by-point accuracy. One GIFF file per layer reflects
the number and position of each point of every individual layer. Material droplets from
the print head are then allocated to each point. Therefore, a certain materiality can
be determined for each point of the GIFF file. The system employs three print heads,
more can be added. The system then reads the GIFF data and processes the material
distribution per layer. The print heads spray or jet between 30,000 and 100,000
material droplets of high viscous plastic onto the building platform. Electric tension
is used to direct the individual droplets such that they are a perfect rendition of the
building plan. The high resolution makes it possible to generate true gradients: A string
of material can be printed in a spiral with a density of 100% on one end and 0% at the
other. A transparent carrier material serves as support structure.
The system can also create vertical ‘walls’ only a few droplets wide – without support
material and without the inherent viscosity of the material causing the ‘wall’ to be
instable. This can be achieved because of particular material properties; a material
developed by TNO. The carrier material is a polymer paste that can be filled with
different powders. The filling can consist of ceramics, plastics or metals; which in turn
can be used to vary the material properties of the manufactured parts.
A particularity of this system is that the building platform moves underneath fixed print
heads, instead of the print head moving over the platform as is typically the case.[7]
The TNO system is a specialty in the series of developments in Additive Manufacturing
because the system technology followed a unique approach. Freedom of form is
complemented by freedom of material – programmable gradients open up a variety of
new constructive methods, for example for fittings or the manufacturing of gradient
materials.[7]
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Print-On-Glass
The possibility to capture material distribution via image files and to materialise these
images with an according system has lead TNO to develop another method. Print-OnGlass means using a software tool to translate images and graphs into RGB pixels which
are transferred onto float glass panes with a ‘glass printer’. Coloured glass particles in
powder form are distributed by a print head analogue to the image file. The result is a
representation of the original file on the glass surface which is then burnt-in in a glass
kiln to permanently bond it to the float glass. The final coloured glass panes are made
of one monolithic material.[8] The idea of ‘Direct Glass Fabrication (DGF)’ derived
from this concept. With DGF several millimetre thick structures are created instead of
building up a thin layer of glass powder onto a glass pane (see § 4.2.2).[8]
Figure 89
Left: Beta system of a glass powder printer at TNO in Eindhoven; the principle was adopted by Saint Gobain Glass and is now
commercially used for façade projects.
Right: Application of the glass powder printer for the ‘Beeld –en Geluid’, Hilversum; all glass panes in the façade are individually
coloured with printed glass powder particles.
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Digital Light Processing
AM process
Digital Light Processing
Abbreviation
DLP
Main-Application
Manufacturing: hearing aids, casting cores for jewelery
Material
plastics: light curing resins;
Epoxy, Acrylic, Wax, Silicones
Invented by
EnvisionTec, Germany
Year
2003
Manufacturer
EnvisionTech
DWS Systems
Building Chamber (mm)
457x304x508
110x110x70
Material
Photopolymer resin
Photopolymer resin
System
Perfactory Xede
DigitalWax 029J
URL
www.envisiontec.com
www.dwssystems.com
Further information
A few hundred dental prostheses can be manufactured with one build job on a DLP system.
Individual geometries allow for customized fitting. The ‘printed’ prostheses are casted in different materials from the DLP-part.
Using DLP for the manufacturing of fine-casting cores for jewellery, very accurate detailing can
be achieved.
Figure 90
Schematic drawing DLP method
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Figure 91
Casting modells for jewellery produced with DLP
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With DLP, a fluid resin – so-called photopolymer - is cured by means of exposure.
The photopolymerisation process is based on the projection of UV light masks over a
mirror matrix across the entire building platform. The building plan of an entire layer is
exposed with an ‘image’ and not, as with laser sintering, traced with a light source. The
image is projected onto the surface of the building platform as a bitmap mask. Hereby,
the process chamber is filled with fluid photopolymer. Exposed, i.e. unmasked areas
are cured. One particularity of DLP is the continuously rising building platform. Firstly,
the models are created upside down and secondly, the model grows continuously.
This eliminates the stepped surfaces and visible layers typical for other systems; the
surfaces are smooth and highly accurate. The resolution is between 15 and 150 µm;
which is significantly higher than that of other methods.
Therefore, this method is used to manufacture jewellery (casting moulds) and toys as
well as for medical engineering (dental prosthesis, hearing aids). For products used in
medical applications, biocompatible materials are used that can be implanted into or
worn on the body. To create customised dental prostheses, the DLP models are cast in
gold, ceramics and other specialised materials in a subsequent process. One building
job can produce several hundred individualised dental prostheses.
Due to the high resolution, the method is well suited to produce filigree cast blanks for
jewellery.
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Laminated Object Manufacturing
AM process
Laminated Object Manufacturing
Abbreviation
LOM
Main-Application
Prototyping
Material
Material sheets: paper, PVC, Aluminium
Invented by
Helisys, USA (afterwards: Cubic-Technologies, USA)
Year
1991
Manufacturer
Cubic Technologies
Fabrisonic (Solidica)
M-Cor Technologies
Building Chamber (mm)
170 x 220 x 145
110x110x70
277 x 190 x 150
Material
PVC
Aluminium, copper, stainless
steel, titanium
Paper sheets
System
SD300
Ultrasonic Consolidation
Matrix 300
URL
http://www.cubic­
technologies.com/
http://www.fabrisonic.com
http://www.solidica.com
www.mcortechnologies.com
Further information
The LOM was invented in 1991 as an independent development since it is fundamentally different from the other methods.
This method no longer plays a role in today’s AM industry because the post-processing requirements are too time-intensive and the processing speed too low.
The first systems were used for product design because the manufactured prototypes made of
paper were easy to post-process (sanding, cutting).
The LOM technology is an independent method that is significantly different from
the other methods in terms of the form of the material and the method with which a
model is generated. The building material is supplied as sheets of material that are
stacked on top of each other and then glued together. The sheet of material is pulled
from a roll across the building table, or laid on it if provided in single sheets. Depending
on the material, the individual sheets of material are either heated and glued with a
melting drum (Paper, PVC), or wetted and bonded with appropriate glue. The contour
of the model is cut with a CO2 laser or a knife blade; the remaining areas are first used
as support structure and pre-perforated for later removal. They remain part of the
geometry until the process is complete. Upon completion they must be separated and
removed; a difficult task in case of filigree or complex geometries.
Since its invention, several companies further developed this method. Therefore, there
are LOM systems that work with different materials: ‘Ultrasonic Consolidation (UC)’ by
the company Solidica, USA; hereby aluminium sheets are used as building material.
The individual layers of material are bonded by ultrasonic welding, and then cut with
a laser. The material properties of the resulting aluminium model match those of
aluminium formed with conventional methods.
The method developed by the Israeli company Solidimension replaces the originally
used paper with a PVC foil; a reversing blade is used to cut the contours of the
geometry.
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The newest development by the company M-Cor Technologies turns the method into
an economic alternative for schools and universities. Inexpensive Din A4 printer paper
us used as building material.
With LOM, the accuracy does not quite match that of other methods. The advantages
for the user are the haptic experience and the appearance of the models as well as the
low cost of material. If paper is used, the models display wood-like structures and can
also be reworked like wood. Usually, the models are used to develop prototype shapes
or as a core for a subsequent process. Enclosed geometries pose a problem in terms of
removing unused material; therefore the shapes are typically limited to planar parts
that might be turned into three-dimensional volumes by folding.
Figure 92
Schematic drawing LOM method
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Figure 93
One available product for LOM by Solidimension; using PVC film
(bottom, right) for part production.
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Characteristic tables of large scale AM methods
Contour Crafting
AM process
Contour Crafting
Abbreviation
CC
Main-Application
Manufacturing: shelter and housing
Material
Other: fibre reinforced concrete
Invented by
Behrokh Khoshnevis, University of Southern California (USC), USA
Year
Manufacturer
USC - Viterbi School
Building Chamber (mm)
6000x6000x6000
Material
Concrete
System
Beta system
URL
http://www.contourcrafting.org/
D-Shape
AM process
D-Shape
Abbreviation
Main-Application
Manufacturing: big scale sculptures
Material
Other: stone powder, marble powder, sand
Invented by
Enrico Dini, Italy
Year
2009
Manufacturer
Monolite, UK
Building Chamber (mm)
6000x6000x6000
Material
Stone powder
System
Beta system
URL
http://d-shape.com
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Fabbing
Introduction
In parallel to ‘industrial’ or ‘professional’ AM applications, another branch of the
methods has evolved since their invention that is summarised here under the term
Do-It-Yourself (DIY). All the methods described hereunder have the goal to offer
‘Personal Fabricating’; i.e. the production means should be accessible to all consumers.
Consumers of today’s mass products are to be made into ‘prosumers’, to producing
consumers. Additive methods are seen as a tool to make the ‘prosumers’ independent
of mass producers. Everybody should have the opportunity to create their own,
individual environment. The phrase ‘Democratisation of production’ encompasses
different approaches to achieve this goal: One approach is to provide young adults with
intensive training to discuss everyday items and to understand their own consumption
behaviour. This is supported by ‘FabLabs’ worldwide. Here, people relearn to develop
and create things themselves, using today’s technical possibilities of digital production.
AM is one building block that makes it possible to design products, produce them in
small quantities and further develop them in user communities.[9]
RepRap
RepRap (derived from ‘Self Replicating Rapid Prototyper’) is an invention by Dr. Adrian
Bowyer and his team of researchers and developers at University of Bath, England. The
first RepRap is called Darwin1 because it is the starting point for its own independent
multiplication. Darwin1 can be used to print many of the parts required for subsequent
systems. The first RepRap was reproduced in April 2008. In order to operate the
RepRap, additional mechanic and electronic hardware components must be purchased
(metal rods, the building platform, cables and PCB, etc.). All assembly drawings, the
necessary data to print the parts and the operating software are available as ‘open
source’ files on the RepRap homepage. One RepRap costs between approximately
400 and 1000 US-Dollar, depending in the desired model and type of delivery (kit or
assembled). A map (Google Maps) shows the distribution of the systems via worldwide
RepRap locations.
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Figure 94
RepRap, Darwin1; Developed at University of Bath, England.
Figure 95
RepRap inventor Adrian Bowyer (left) with first and second generation of RepRap
The system functions like a FDM system: Plastic is melted through an extrusion nozzle
onto the building platform. The effect of the temperature lets the layers of strings of
plastic bond to each other. The print head is mounted to a mechanic system of rods
that can move along the x and y axes. Building up the height of the model is achieved
by lowering the work platform.
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The material used is polylactic acid (PLA). PLA is a biodegradable polymer created
from lactic acid. The lactic acid can be fermented from corn which makes RepRap
independent of industrial products.
Adrian Bowyer’s slogan is ‘wealth without money’. The underlying idea is to break down
the interdependency of wealth and production means. If all necessary consumer goods
can be produced by the consumers themselves by offering inexpensive manufacturing
methods, the market will no longer be determined by a network of production facilities
and means. Scientists develop building materials based on starch to eliminate the
dependency on materials made of raw oil. Any user owning a small piece of land
could generate starch from growing crop on the property, and use this as a renewable
material for the RepRap. A positive side effect is the fact that printed items no longer
in use are easily compostable. The researchers’ goal is to build a machine that can be
used for the most diverse applications. In contrast, the professional systems of the
AM industry are highly specialised machines that are strongly limited in their range of
application.[10]
[email protected]
[email protected] is an invention by Prof. Dr. Hod Lipson at Cornell University in Ithaca, NY,
USA. A list of materials and a construction and user manual can be downloaded from
the internet. And therewith an inexpensive kit. Alternatively, commercial vendors offer
customised kits and pre-assembled systems for approximately 3000 US-Dollar. The
basic idea is similar to that of RepRap.
The system also functions like a FDM system: Fluid or pasty material is squeezed
through an extrusion nozzle (in this case a disposable plastic syringe or similar). The
nozzle is mounted to a mechanic system of rods that can move along the x and y axes.
Building up the height of the model is achieved by lowering the work platform.
Any type of sprayable material such as silicone, acrylic, epoxy resin, clay, modelling clay,
gypsum as well as chocolate, spread cheese and icing can be used.
The system can be equipped with a second extrusion nozzle so that two materials can
be printed simultaneously.
The resolution and surface structure depends on several factors: Property and
consistency of the material, spraying speed, heat supply at the nozzle, and speed of the
aggregate movement.
[email protected] is well suited for experimental work in DIY or educational facilities. The
advantages over industrial systems are ‘open source’ data processing, low initial
investment, material diversity and low material cost.[11] The cost for a [email protected] lies
between 1900€ for a kit and 2800€ for a ready-to-use printer.
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Figure 96
[email protected] (left); extrusion nozzle (right) with medical syringe as the nozzle device.
Summary ‘fabbing’
The DIY applications described here do not primarily focus on the development of
the AM technologies; but rather show the inventive spirit of the 21st century. This
spirit is closely linked to the current technologies and therefore leads to Additive
Manufacturing.
There are many different kinds of DIY-kits and different fabber systems available. To
name just a few more, there is the MakerBot’s ‘Thing-O-Matic’, there is the ‘fabster’ by
FIT GmbH, there is the ‘RapMan’ and the ‘3Dtouch’ by Bits from Bytes, the ‘Fabber’ by
Napster and many more.
All of them offer much scope for do-it-yourselfers and tinkerers. In combination with
other DIY tools, a system can be enhanced with self-fabricated hardware parts. Again,
the underlying principle is that of the FDM method.
All kinds of materials are being processed with fabbers: spread cheese, silicone,
chocolate, dough, wax, human tissue cells, wood polymer, sugar and many more.
The individual kits are also targeted toward very different user groups: RepRap,
MakerBot and others gear toward pupils and students who enjoy putting together
a machine. Therefore, these systems are often found in technical classes at schools
or universities with a background in engineering. Other vendors focus on the do-ityourselfer at home, who finds fabbers to be an enhancement to other manufacturing
methods for building models and realise inventions. Typically, these fabbers are ready
to use and work with the plug-and-play principle. Inexpensive 3D modelling software
leads in the direction of product development; however, usually more as a means to an
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end rather than in the sense of using the possibilities in designing with AM.
It is notable that a few years after fabbers began to spread, commercial manufacturers
from the professional AM market segment complement their portfolio with low-cost
3D printers. One motivation certainly is customer loyalty and the attempt to spread
knowledge about these technologies.
Fabbers are definitely no competition for professional AM systems, but they do
represent a growing market.
Sources related to the technologies:
The information about the methods described in chapter 2 and 6 A are gathered from
the following sources: [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]. The internet
pages stated also point toward further information by the system manufacturers (see
appendix A II / Weblinks). The descriptions were enhanced by personal conversations
between the author and technology users and developers in meetings, at conferences
and trade shows.
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Software
AM file format
One important factor when developing new applications for AM technologies is the file
format used to edit, render and reproduce 3D geometries. The STL format developed
during the eighties by 3D-Systems is no longer accepted by all suppliers and users since
it is too limiting. In addition to the STL format there are more than twenty independent
developments, each with their own advantages and disadvantages, but none of them is
generally accepted.
Since 2010, a group of participants from system manufacturing, software
development, science, AM associations as well as user groups work together on
developing a universal data format. The work title is ‘Additive Manufacturing File
Format (AMF)’; and the development is conducted under the patronage of the
American Society for Testing and Materials ASTM. The goal is to develop a format
that is supported and accepted by all users. It should stand against the multitude of
insufficient alternatives currently available, and offer technical advantages over the no
longer adequate STL format. One such advantage is compatibility between the different
digital tools. Currently, complications often occur when exchanging files between input
and output devices such as scanners, graphic cards and modelling software.
Another issue of the STL format is a limited possibility to store additional information
in the file. In the early days of AM it was sufficient to define the surface properties
by specifying edge definition and orientation; however, today’s improved system
technology demands that we can also determine information such as colour, material,
texture, support structure, and orientation within the process chamber, amongst
others. The requirements are mostly driven by developments in the fields of multimaterial printing, multi-colour printing, and creating gradient materials.
The AMF file format should allow an easy exchange between all 3D input tools and
AM output devices. Similar to the PDF format that offers problem-free exchange of
digital documents in computer applications. The ASTM development should be openly
available, not be subject to any copyright, compatible with any available system, and
upgradeable for future enhancements. The involvement of all key companies and key
persons from the AM industry shall preserve the ‘open source’ approach.[21]
Another factor is that as the files grow in complexity they grow in size, too. But there
are technical limits in terms of generating, storing, sending and using large data files
for production. The STL format does not aid in reducing the file size. By using ‘dumb’
vectors to describe geometries, all edges of a body, for example, are represented by
two, ideally identical vectors of different triangles. The results are unnecessarily large
files and risks of error. Improving the part tessellation (the degree of approximation
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of 3D planned geometries and the resolution of the AM output device) through better
vectorisation and triangulation can help.[22]
Currently, 3D geometries are only described and defined via their edges and surfaces. It
was therefore sufficient to specify the edge vectors and surface orientation of a volume.
This is true for those programs called ‘surface modellers’ as well as for those that work
with so-called ‘solid modellers’. Using parameters for ‘filling materials’ to create a
shape is not (yet) included, but is the key factor for gradients within a part. The goal is
to define a body via voxels (Volumetric Pixels). Existing methods circumvent such voxel
programming by representing the volume in bitmap files; however, this mandates a
non-universal computer language.
CAD software
Besides technical limitations, the use of AM is also limited by the currently available
software to create the necessary CAD data sets.
Even professional software hits a barrier concerning the development of functional
constructing for AM. Most programs are designed to represent and generate surface
areas. Even though some of these programs do have the capability to process additional
information they are not designed to handle grid structures, material gradients or other
quantity-intensive shapes. Usually, such designs result in drastically slower processing
speeds, infinitely large files and often failure of the software application. Similarly to
the AM hardware, which is coined by its evolution from the early prototyping systems,
the software is also coined by previous applications, and not by the requirements of
production with AM. Fundamentally new developments are required for AM and AM
system technology to achieve easier handling of the 3D data. Data transfer to and from
utility programs must be guaranteed, and the development of specialised software for
design, simulation and manufacturing of AM parts must be pushed on.
It still takes expert knowledge to develop products in virtual space. The design process
will only undergo a comprehensive change when user friendly and easy to learn
software tools are available for such complex AM developments.
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Additional information on the research results
Technical drawings T-Connector
Figure 97
Technical drawing of the standard T-connector for a stick system; used as digital background for optimisation.
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Figure 98
Technical drawing of the standard T-connector for a stick system; details and dimensions for the optimisation
process. All screw channels and technical features were re-constructed in the advanced connector.
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Figure 99
The first adjustment was the implementation of two different angles; this would allow for deformation in the
façade.
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Figure 100
Optimised part as result of the optimisation for AM; in this part material was digitally ‘cut off’, where it is
structurally not needed.
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Technical drawings façade node – Nematox II
Figure 101
Technical drawing with real dimensions of the Nematox II; top view.
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Figure 102
Technical drawing with real dimensions of the Nematox II; front view.
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Figure 103
Technical drawing with real dimensions of the Nematox II; side view.
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Figure 104
Technical drawing with real dimensions of the Nematox II; isometric view.
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SWOT Analyses: AM in the façade industry
A SWOT analysis collects ‘Strengths’, ‘Weaknesses’, ‘Opportunities’ and ‘Threats’
closely connected to a particular project, a company or business venture. It is a way to
find and specify factors that are favourable or unfavourable to achieve the objectives
of the project or enterprise. At first, it is only a collection of aspects and factors. In a
second step, the results can be used to draw conclusions and / or develop strategies.
SWOT analysis gives an overview of individual aspects in a field of investigation. In
this case the charts show strong and weak aspects of different main topics (‘Aims’)
concerning the use of AM for Kawneer. The original aim of SWOT to compare internal
and external of a certain topic was changed in the given charts to a ranking of weak and
strong aspects because AM is not yet applied by Kawneer.
The five SWOT charts are followed by an interpretation of the resulting aspects to
provide a resume of the charts. (see [23] [24] and [Wikipedia])
SWOT 1: AM for façade system provider
Aim: to become AM producer in the own company.
Strong
Weak
Opportunities
- be the early adopter
- gain AM knowledge
- develop AM strategies
- engineering to company needs
- branding for the company with AM
- adjust DMF process to company needs
- control of processes/innovation
- new materials for façades
Threats
- certification
- cost per piece
- initial investment high
- liabilities for DMF parts not clear
- fit AM into existing façade systems
- risk of failure of technology
- risk of failure in marketing
- limited size of parts
- accuracy / finishing
- time consuming production
- time consuming designing
- no long-term experience yet
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SWOT 2: AM for One-Off Solutions
Aim: apply AM to show its potential in a ‘Abu Dhabi Façade’.
Strong
Weak
Opportunities
- show possibilities
- ‘AM inside’ branding
- test-drive AM parts
- push the limits
- amortize first system fast
- adjust AM strategies
- start a demand in the market
- acquire new customers
- train contractors
Threats
- time consuming production
-designing and scripting complicated
-limitations for whole façade unknown
- cost per Node
- post processing unclear
- tolerances in the façade
- movements in the façade
SWOT 3: freeform for aluminum façades
Aim: show if freeform design is the choice for existing post-and-beam systems.
Strong
Weak
Opportunities
- start from far developed system
- need for change in the market
- improvement in Stick- façades low
- new discovery desperately needed
- ‘file-to-factory’ possible in façade industry
- optimized part geometries for minimized material
consumption
- marketing success
- fool proof solutions
- less waste in production
Threats
- limitations from stick-system
- limitations from glazing
- design limitations
-need for specific architectural design
- market request low
- material limitations
SWOT 4: metal for freeform façade solutions
Aim: application of alternative materials for an enhanced façade system.
Strong
Weak
Opportunities
- well known properties
- same material as standard profiles
- strong
- easy to post-process
-aluminium available (for most stick-systems)
Threats
- heat conductivity
- need for thermal break
- expensive to ‘print’
- more complicated to ‘print’
- heavy
- limited in material performance
- not gradable
- deformation
- limited size in AM
- repeatability not clear
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SWOT 5: DMF as method of choice for the presented parts
Aim: evaluation of printed parts.
Strong
Weak
Opportunities
- ‘real’ material
- strong enough
- impression of ‘real’ part in mock-up
-same material as for standard profiles
- post processing possible
-properties like existing standard parts
Threats
- price per part / mock-up
- production more complicated than ‘printing’ plastic
parts
- production time
- low expertise in metal-design
Resume
To optimise the results of the SWOT analysis and to make use of the Strengths and
Weaknesses shown, it is necessary to find suitable ways / strategies that can be
followed. To do so, there are combinations of the S, W, O and T, that will give some
hints about the results from the listing of the aspects.
S-O combination
To be an early adopter has opportunities as well as downsides. For marketing purposes,
it is certainly right to:
• invest into AM research;
• try to adopt AM for production.
The combination of some of the found opportunities offers benefits:
• by using AM early, the company can get thorough insight into the feasibility of
projects in advance;
• by training their staff early on, Kawneer could become known as an expert
consultancy and/or gain leadership in the façade market.
S–T combination
Which Threats can be counteracted by which Strengths? By using which Strength can
we ease/relief possible Threats?
• Developing an expertise in AM for façade applications offers the opportunity to
create new markets/market shares.
• This transfer can only be realised by knowing the full capability of AM technology.
For example, by demonstrating potential customers that 3D controlled façade
nodes make the simulation, control and mounting of individual façades viable.
• New marketing strategies can derive from DMF parts (the ‘Abu Dhabi Node’).
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W–O combination
How can Weakness be transferred into Strengths for single aspects of the analysis?
• Being an early adopter can, for example, the company can be the first to establish
hitherto non-existing certificates in the market. Therefore the experience and
expertise will grow. The company can get ahead of the competition.
• Only if the technology is used extensively, will the price per piece drop. The more
investigation is put into new applications, the faster the investment will pay of.
• Limitations within the (extensively) developed stick system may lead to new
impacts for the system itself, maybe to a re-interpretation of the post-beam façade.
W–T combination
What is the weakest point, how can it be addressed?
• Investing into future innovation is always a risk. The chance to participate in the
return of investment is high if the ‘product’ succeeds.
• Liabilities / certificates are inevitable. By ‘test-driving’ first parts, the company
becomes the pioneer in AM for façades.
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Spread the idea - ideation with AM
The response to the technology was tested in different workshop situations with
different groups of participants such as students, researchers as well as architects and
planners.
To be able to judge how architects perceive the AM technology for their own field
of expertise, two meetings were organised during the research project. Both were
conducted at renowned architectural offices in the Netherlands and Germany. To limit
the topic to the scope of the workshops, it was based on ideation. The AM technologies
were introduced and guided workshops were conducted. The results are a colourful
mix of intuitive ideas – some very abstract, some closer to reality. But considering the
short amount of time invested to develop these sketches (approximately half a day) it
is obvious that brainstorming with likeminded people leads to an amazing potential for
invention.[26]
The setup of the workshop was the same for both events in order to be able to compare
the two different groups of engineers and designers, and compile a critical resume for
the façade industry/Kawneer. The topic for both meetings was ‘SKIN and NATURE’ to
stimulate the ideation process and find a connection to the building envelope.
Figure 105
Different phases of the ideation process.
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Phase 1 / Briefing
In the beginning of the ideation process, manifold impressions and associations from
different areas are collected: Lectures and information exchange build the background
of the continuing imagination process. To think outside-the-box and to collect input
for the ideation is necessary during this phase.
Phase 2 / Associative brainstorming
For both topics - ‘Skin and Nature’ - all appearing terms are collected in a freely
associative manner. There is no need to link these terms directly to architecture or
façade technology. The variety of ideas and combinations will actually benefit from
neglecting the ‘main topics’ and will become broader. The more the participants
open up their minds to associative thinking, the more combinations will appear in the
following steps.
Phase 3 / Initial ideas
Combinations from both fields are selected from the terms collected in phase 2.
Depending on the available time, two to five pairs are possible as a starting idea. These
pairs then form the basis for further ideation. A first assessment of the rough idea is
possible (indicate size, define group of materials,…).
Phase 4 / Evolution
The ideas from phase three are presented, explained and discussed by the group. The
most promising ideas are followed up on. Combinations of initial ideas into one new
idea are possible. After the second presentation to the group the teams will further
develop the strongest result into a more complex vision.
[25]
Regarding ‘AM Envelope’, you can find those kind of visions in § 4.2, as they were
generated in the same manner in various gatherings.
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UN Studio, Amsterdam; held on April 29th, 2010
Participants:
UN Studio: Astrid Piber, Abhijit Kapade, Christian Veddeler, Cynthia Markhoff, Ger
Gijzen, Hisa Matsunaga, Joerg Lonkwitz, Jordan Trachtenberg, Juergen Heinzel, Juliane
Maier, Luis Etchegorry, Miklos Deri, Mo Lai
Kawneer-Alcoa: Jeroen Scheepmaker, Klaus-Martin Hees, Michel van den Berg
TU Delft / Hochschule OWL: Ulrich Knaack, Holger Strauss
A general first result was the identification of a broad range of application
opportunities. The technology was not yet recognised in the field of architecture.
The resulting ideas stimulated the responsible office partner to work out life-size
applications for some of the concepts. However, the limitations caused by a lack of
certified materials and certifications for building applications will inhibit the use in
‘real’ architecture. One option to trigger the process could be to realise interior design
items that derive from the workshop results. Everyone was open to test-drive AM
technologies.
The focus of the brainstorming sessions was restricted to façade solutions alone
but covered a brought range of ‘architecture’. Therefore the results were not directly
connected to Kawneer façade systems, but demonstrate that AM could become a
general branding aspect and opens up new ways of reinterpreting existing solutions.
Behnisch Architekten, Stuttgart; held on May 4th, 2010
Participants:
Behnisch architects: David Cook, Martin Haas, Maria Kohl, Stefan Rappold, Isabel von
Schmude, Patrick Certain, Frank Kimpel, Dominik Heni, Lisa Dengler, Stefanie Platsch,
Samuel Schmidt, Christian Zwick, Christian Goldbach, Matthias Ryntowt, Theresa
Kessler
TU Delft / Hochschule OWL: Ulrich Knaack, Marcel Bilow
At Behnisch Architekten, a renowned architectural office in Stuttgart, the response was
similar to the one stated above. The consensus here was that the technology was only
known for the production of display models in design competitions. Applications from
Rapid Manufacturing and mass customisation (see § 4.3) were new to the participants
who found the idea very interesting. The fact that AM can be part of an everyday
production chain, for example in the medical field, was perceived positively; with the
result that the participants discussed future application in an architectural context.
Right now, Behnisch Architekten has no application possibility for AM; however they
are keen on following its evolution.
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Figure 106
Imagination workshop at UN Studio, Amsterdam, May 2010.
The strongest limitation is seen in the price of the technology and of the parts.
Opportunities for the application of AM are seen in the field of freeform steel
constructions or individualised fittings for architectural solutions.
At the end of the workshop the use of multi-material parts was considered and
discussed related to their implementation into electronics and sensors for an enhanced
living environment (for example living for elderly people).
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Standardization
No quality standards or norms have yet been established for AM products. In order to
be able to compare the products to one another and to conventionally manufactured
mass products, traceable and comprehensible criteria must be established in the AM
industry. The quality of the manufactured parts, the quality standards for the methods
and materials available as well as quality control of the individual methods are key
factors for the development into an universally accepted manufacturing method.[16]
But just as work groups of ASTM (American Society for Testing and Materials) are
dealing with various aspects of the AM technologies, there are efforts to define and
establish exactly such test procedures and quality management (QM).[27]
System manufacturers have also acknowledged the importance of establishing a QM
system. Thus, since 2010 there are visible efforts by the manufacturers to integrate
quality control in their systems. ConceptLaser, for example, has established a QM
system in its LaserCusing equipment: A protocol is generated for each produced layer
which can be allocated to the built part and manufacturing process, and possibly each
exposure cycle during the building process. This allows tracing the heat intensity at
the melting point of the laser, and thus conclusions about material properties and
the quality of the sintered part. EOS developed a QM system with protocols and test
volumes that allows the user to retrace process parameters and document material
properties. The protocols are generated for each manufactured part and serve as an
assurance for the end user that the system was properly calibrated and serviced, and
that the process parameters of two different process cycles were identical.[28]
Regulation and standardisation of the methods will play a key role when applying AM
to façade or building technology: When dealing with façade components, it is not
only important to ensure proper performance and design, but even more so to ensure
human safety. Standardisation and regulations are mandatory to avoid having to
receive individual approval for each and every application.
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Inspiration from bio-mimicry
One common argument for the use of AM technologies is the possibility to generate
free-formed parts without the need for tools. And such free-form designs are usually
associated to shapes in nature – thus, the step to implement or transfer bionic
principles is apparent. ‘Digital availability of bionic principles’ makes it easier for
engineers and planners to create resource-friendly constructions; skeletal structures,
honeycomb structures or even organic structures can be digitally planned, controlled
and optimised. What needed to be illustrated, tested and manually translated into
technical drawings when Frei Otto and Antoni Gaudi were trying to find shapes for
load-bearing structures ‘optimised according to the laws of nature’, is made easier and
accessible to all by the availability of digital tools today.
Considering global warming and the ongoing discussion about sustainability, the
building industry and therefore planners and architects must also think of how to
handle resources in an environmentally friendly manner. Additive methods open up
one possibility to save material. Separately from the debate about primary energy,
building constructions should be accordingly optimised. This is true for structural
building parts of skeletal load-bearing systems as well as for ‘massive’ constructions.
Optimisation modelled after nature can avoid unnecessary material consumption or
possibly reduce material waste through increased performance of existing systems,
which would lead to a reduction in overall material use.
Constructive lightweight building is the most obvious application offering the potential
for material savings. It is already used in parts of architecture (and interior design).
Generative methods could stimulate a more extensive transfer of the lightweight
principles to hitherto untouched building components and constructions. Optimising
building parts analogue to nature inevitably leads to geometries that can usually
not be realised with conventional tools or for which conventional methods are not
optimally suited. Methods based on layering are one possibility to overcome this. They
allow manufacturing constructions without cut waste; already optimising material
consumption during production.
As part of the ‘green’ discussion, one of the engineers’ tasks is to rethink and optimise
existing constructions with suitable digital tools. Starting points hereby are shape
optimisation (for example with ‘CAO: Computer Aided Optimisation’, according to
Mattheck [29]), topology optimisation (for example with ‘SKO: Soft Kill Option’,
according to Mattheck [29]), but also simulation and iteration of the modified parts
with software applications (Finite Element Analysis, realisation in CAD).
Transferred to the requirements of a façade, the buzz word bionics alone can bring
about many new ideas for improved application: Shading, light directing, load transfer,
layering, etc. are only a few aspects that can be changed with AM motivated bionics
(see § 4.2).
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New markets from AM
Spreading new technologies must be tied to the large market developments. To
evaluate the potential of a new technology we need to assess its influence on the
market: Does the technology already exist in the market or will it remain a specialised
niche product? Can the technology spread out; can it open up new markets?
‘Conventional’ markets and industries have noticeably become aware of the additive
methods: if not as a production method, at least as an “emerging technology”.[33]
The market watches out for and evaluates such ‘new technologies’ in order to be able to
estimate their potential. This means that indications about regional and global trends
toward changing production methods can be gathered. Such scenarios can also help
in deriving the development of additive fabrication. It must be noted that over the past
few years the ‘3D Printing’ technology – conversational term for AM technologies –
has appeared on the scene in many configurations; a fact that supports the desire and
visions proposed in this work. This allows the conclusion that this technology offers
great potential; a fact that is noticed even outside of the sworn in AM community of
users and suppliers.
The overall development of ‘3D printing’ (without specification) or specific applications
(for example in the medical or aeronautics industries) are looked at or explicitly stated,
but the technology was never yet associated with the building technology. However, any
professional market analysis predicts great potential for AM (Gartner, 2011; Wohlers,
2012; IBISWorld, 2012).
“The demand for products and services from additive-manufacturing (AM) technology
has been strong over its 22-year history. The compound annual growth rate (CAGR) of
revenues produced by all products and services over this period is 26.4%. The CAGR
slowed to 3.3% over the past three years, with 2009 being the slowest in many years,
by far. The chart shows the rate of growth/decline since 1993. The bars for 2010 and
2011 are forecasts.
Unit sales remain relatively strong due to the impact from very low-cost machines.
The 3D printer market segment grew by nearly 18% in unit sales, yet the segment
experienced a sharp decline in revenues—the first time ever since tracking this market
segment.
The additive-manufacturing industry has tremendous untapped potential, especially
when considering the opportunity in custom and short-run production. Producing
parts for end use products is more challenging than models and prototypes, so this
application will take time to develop. It is expected to drive revenues from AM products
and services to impressive levels in the future.”[30]
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Figure 107
AM market development and growth rates; source: Wohlers
Associates; report 2010. “The previous chart gives estimated
revenues (in millions of dollars) for additive manufacturing
products and services worldwide. The lower portion of the bars
indicates products, while the upper portion indocates services.
The bars for 2010 and 2011 are forecasts.”
Figure 108
Expected Growth of Additive Manufacturing for Part Production
Applications; source: Wohlers Associates; report 2009.
Another market analysis by IBISWorld conducted in 2012 also lists Rapid (AM)
technologies under the Top 10 of the “emerging technologies”. By means of this Top
10 list, the analysts of IBISWorld try to identify trends that promise large growth and
thus newly developing or – conversely – decreasing markets. The IBISWorld surveys
exclusively represent the US American market; however, they do reflect approximately
700 important industry sectors.
“Rapid technological advances, falling costs and a greater need for new medical devices
have led to the growing presence of 3D printing […]. The 3D Printer Manufacturing
industry’s revenue has grown an average of 8.8% per year since 2002, with 20.3%
growth expected in 2012 alone. As the cost of producing these high-tech machines
decreases and printer technology is refined, they will be used for an increasing number
of applications, such as aerospace-related part manufacturing. With the rapid pace of
innovation already present in the industry, double-digit annualized growth (14.0%) is
projected to continue into the next five years.”[31]
Noteworthy is a generally positive development in the market segment ‘Additive
Manufacturing’, and a good prognosis for business opportunities, enhancements of
existing productions and adaptation for new areas (for example the façade). Based
on a market study, the development for the AM market can be summarised such that
companies working with AM estimate that in the next five years production of AM
products will represent as much as 36% of the business activities. The ten year prognosis
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lies at more than 50% – compared to a mere 16% in the year 2008.[30]
Various sources consider the development of the AM technologies positively (Gartner,
2011; Wohlers, 2012; IBISWorld, 2012), and a detailed review shows continuous growth.
In order to estimate the development of the different AM methods related to
façades and building construction, aspects of a possible business model with AM
were considered in addition to those with concrete building practical applications.
The results can be illustrated in a developmental ‘AM roadmap’, which visualises
subsequent steps and technological changes, and puts them into chronological order.
To do this, already formulated ideas and possible applications were allocated to
different ‘branches’ of the AM technologies. Thus, the roadmap shows the progress of
a possible development in terms of technological sophistication and the contextual
interdependency of different ideas. Again, this procedure shows that applying AM to
façades requires a large number of intermediate steps. Besides these main paths, the
roadmap also shows various side roads and common way points.[24]
Figure 109
AM roadmap (revised by the author according to Volkers, 2010)
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At the end of the roadmap [24] are three concepts related to applying AM to façade
technology:
• the Fully integral Façade (FiF);
• the Façade Machine (FM);
• the Super Smart Skin (S³).
These points on the path to a dynamic building envelope illustrate three differently
motivated façade developments based on current experience and requirements
(see § 3.1) and the current state of technology of AM (see § 2.2). Independent of
production reality and contrary to the research results shown in chapter 3 these visions
identify possible areas of development. They are examples of imaginative visions
whereby ‘FiF’ (see § 4.2.1 / Fully integral Façade) probably comes closest to an AM
building envelope in terms of consequently reinterpreting the building envelope.
To create the roadmap, the first step was to consider the prospect of an industrial
application of AM technologies and its transferability to economic use.
Here for, companies must estimate and assess the potential for their own business. The
decision of whether or not AM can or should be integrated into the production chain
is influenced by external and existing internal circumstances. In order to dare make
a realistic estimation whether AM can play an important role in the façade industry,
such entrepreneurial deliberations must be considered – the development must be
finalised with a proof of economical feasibility. An invention can only mature to a true
innovation if it reaches marketability – and this is also valid for generative methods in
the façade technology.
External factors to consider are:
• key trends (technology trends, regulatory trends, societal & cultural trends,
socioeconomics);
• market forces (market segments, needs & demands, market issues, switching costs,
revenue activities);
• macro economic forces (global market condition, capital markets, commodities &
other resources, economic infrastructure);
• industry forces (supplier & other value chain actors, stakeholders, competitors, new
entrants, substitute products & services).
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Internal factors to consider are:
• customer segments;
• value propositions;
• channels;
• customer relationships;
• revenue streams;
• key resources;
• key activities;
• key partnerships;
• cost structure.
[32]
As mentioned before, AM can positively impact the façade industry. But cost efficiency
and current existing technological barriers are still used as the main decisive criteria;
hindering a ‘fair’ assessment of its true potential. However, AM opens up many
advantages for future business models. The appropriate question to ask is how and in
which area AM technologies can benefit the business model. Currently, the bare costs
of AM might be higher than those of conventional manufacturing techniques. But if
a company can offer better ‘value’, customers might be willing to pay the premium.
Besides savings related to stock keeping and labour, for example, the sum of all aspects
might result in overall saving.[24]
Figure 110
Cost comparison: conventional technologies and AM (Volkers, 2010).
The cost savings shown in figure 110 can have different causes: On one hand, they
can be a result of the cost structure of the product, on the other; they can result from
additional sales revenues. Besides pure cost calculations it is important to consider
the factor ‘time to market’. With AM, sophisticated components can be produced and
distributed in a shorter time period. If the cost savings for a particular product are large
enough they could justify the higher cost for the use of AM technologies.
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And there is the possibility to generate added value beyond the production process:
The number of parts needed for a multi-part product, for example, can be reduced by
generating an appropriate functional construction. In turn, this leads to significantly
shorter assembly times for semi-finished products and final assembly of ready-to-use
parts. Such modifications of the component structure impact other production criteria
as well. Stock keeping, replenishment logistics, assembly, weight and maintenance can
be optimised and thus improve the overall cost of the production process. However, the
critical factor for all such changes is that the awareness and acceptance of developers
and manufacturers must change to allow for a realistic prognosis about the use of
additive methods.[24]
Figure 111
Gartner Hype Cycle 2012, source: Gartner.com.
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Besides the approaches described above to integrate AM into corporate structures, the
‘Hype Cycle’ developed by Gartner in 1995 can be employed as another decision aid.8
For several years now, ‘3D printing’ can be found in the ‘Hype Cycle’ for “emerging
technologies“; the fact that it is listed means that it is considered a notable technology.[33]
In their research on the development of trends and innovative technologies in
Information Technology (IT) they realised that they shared a common pattern. To
illustrate the technologies in the “Hype Cycle” the positioning of the technologies
is described based on product maturity and average market development. These
two factors are plotted onto one timeline, allowing a division of the technological
development into different stages:
• innovation trigger;
• peak of inflated expectations;
• trough of disillusionment, slope of enlightenment;
• plateau of productivity.
Generally, when introducing a new product to the market, an initial euphoric start
is followed by a phase of disillusionment. During this phase, a (possibly) overrated
product meets the real market world with true requirements and the necessity to
sustain its position. Only if it emerges from this trough, the product re-enters a phase
of regeneration, followed by productivity or realistic market development. At this stage,
the product is accepted and valued by a larger circle of users.
Today, many companies base their decisions on the ‘Hype Cycle’. In the meantime
they reflect more than a decade of dedicated knowledge, and are available for different
market segments and are updated annually. The decision aid gives an indication of
whether a company should use a new technology, new process chains, applications or
ideas, and if so, when. Thereby it addresses scenarios that can be based on interior as
well as exterior motivation.[34]
The conservative building market is slow in recognising and accepting such changes.
Relating to the development of façade technologies, the past decades reflect a phase
of increasing specialisation: Fundamental innovation (meaning new concepts that
change fundamental principles) is not apparent. The result is that established building
products become more specialised, detailed and thus complicated. The beginning of
the 20th century saw a ‘rapid change’ of façade constructions within a few years; true
innovation took place – in the form of the curtain wall, i.e. the first true separation of
building structure and building envelope.
8
The information was taken from: www.gartner.com: “Gartner, Inc. is the world’s leading information technology
research and advisory company. We deliver the technology-related insight necessary for our clients to make the
right decisions, every day. Founded in 1979, Gartner is headquartered in Stamford, Connecticut, U.S.A., and has
5,000 associates, including 1,280 research analysts and consultants, and clients in 85 countries”
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Product Sophistication
Improvement
Rapid Change
New discovery
Time
Figure 112
Product sophistication: by Tillmann Klein. In: ‘Integrated Façade Components’
presentation, Spring 2009, Delft University of Technology.
Figure 113
Faguswerk by Walter Gropius,1920. The
first curtain wall façade in Germany.
Since this innovation, the basic principles were continuously further developed
(‘Phase of Improvement’). Again, external factors were the main drivers, such as the
oil crisis during the Seventies: Topics still important today such as energy savings,
heat insulation and energy demand were formulated based on this crisis. The façade
technology responds to such triggers by continuing the development of existing
systems: Single glazing becomes double glazing, then triple glazing – while the effect
is not linear but exponential. Therefore, improvements achieved by the changes of
the past few years can only be measured using third decimal places. A fundamentally
different approach is nowhere in sight. AM could therefore represent a technology that
is part of the digital revolution - bringing about a new discovery that will replace current
standards.[23]
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McKay, D., Burns. Using Fabricators to Reduce Space Transportation Costs, . in Solid Freeform Fabrication
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[2]
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[3]
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[4]
Ulrich Knaack, M.B., Holger Strauss, Rapids - Layered Fabrication Technologies for Façades and Building
Construction. imagine 04, ed. K. Knaack, Bilow. Vol. 04. 2010, Rotterdam: 010 Publishers. 128.
[5]
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[6]
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[8]
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em_id=36. [cited May 2008].
[9]
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innovation. [cited April 2008].
[10]
Uehlecke, J., Von der Zahnbürste bis zur Digitalkamera. Die Zeit Wissen, 2/2007: p. 83ff.
[11]
Lipson, H. [email protected], http://www.fabathome.org/wiki/index.php?title=Fab%40Home:Overview. [cited May
[12]
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[13]
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2005, Camebridge, MA, USA: Basic Books.
[14]
Fabaroni, MIT, http://fab.cba.mit.edu/classes/MIT/863.07/11.05/fabaroni/. [cited April 2008].
[15]
Wohlers, T., Wohlers Report 2007, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2007: Fort Collins, Colorado, USA.
[16]
Wohlers, T., Wohlers Report 2008, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2008: Fort Collins, Colorado, USA.
[17]
Hopkinson, N., R.J.M. Hague, and P.M. Dickens, Rapid Manufacturing. An Industrial Revolution for the Digital
Age. 2006, Chichister, England: John Wiley and Sons, Ltd.
[18]
Neef, A., K. Burmeister, and S. Krempl, Vom Personal Computer zum Personal Fabricator. 2005, Hamburg:
Murmann Verlag.
[19]
Grenda, E.P. Castle Islands Worldwide Guide to Rapid Prototyping. 2012 [cited 2012; Available from:
http://www.additive3d.com/home.htm.
[20]
Burns, M. fabbers.com. 1999 -2003 [cited July 2012]; Available from: http://www.ennex.com/%7Efabbers/.
[21]
ASTM, AMF - AM‘s New File Format, the story so far, in tct magazin. 2011.
[22]
Chua Chee Kai, G.G.K.J., Tong Mei, Interface between CAD and Rapid Prototyping Systems. Part 1: A Study of
Existing Interfaces. Advanced Manufacturing Technology Journal, 1997(13): p. 566-570.
[23]
Ginkel, L.v., Rapid Manufacturing in Façade Design, in Chair Design of Construction, faculty of architecture.
Masterthesis. 2010, TU Delft: Delft.
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[24]
Volkers, N., The Future of Additive Manufacturing in Façade Design, in Chair Design of Construction, Faculty of
[25]
Pricken, M., Kribbeln im Kopf. 2007, Mainz: Verlag Hermann Schmidt.
[26]
Strauss, H., AM Façades - Influence of additive processes on the development of façade constructions. 2010,
[27]
Wohlers, T., Review of Current US AM Market, in tct magazin. 2011, Duncan Wood: Tattenhall, UK.
[28]
Strauss, H., Personal Communication with suppliers and adopters of the technologies on various meetings,
Architecture. Masterthesis. 2010, TU Delft: Delft.
Hochschule OWL - University of Applied Sciences: Detmold. p. 83.
conferences and fairs., t. Author, Editor. 2011: various.
[29]
Mattheck, C., Verborgene Gestaltgesetze der Natur: Optimalformen ohne Computer. 2006, Karlsruhe: Karlsruher
Institut für Technologie. 116.
[30]
Wohlers, T., Wohlers Report 2010, Rapid Prototyping and Manufacturing, State of Industry, Annual Worldwide
Progress Report. 2010: Fort Collins, Colorado, USA.
[31]
MacFarland, L.S.M., Top 10 Fastest-Growing Industries, in IBISWorld Industry Reports. 2012, IBISWorld:
Santa Monica.
[32]
Alexander Osterwalder, Y.P., Business Model Generation - a book for visionaries, game changers and
challengers. 2009: Self-Published.
[33]
Gartner, I. www.gartner.com. [cited April 2012]; Available from: www.gartner.com.
[34]
Fenn, J., Raskino M., Mastering the Hype Cycle - How to Choose the Right Innovation at the Right Time, ed. I.
Gartner. 2008: Harvard Business Press Service. 237.
256
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A II Additional information PhD thesis
Literature
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Fabricator. 2005, Hamburg: Murmann Verlag.
Gershenfeld, N., FAB - the coming revolution on your desktop - from personal
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Van-Bruggen, C., Guggenheim Museum Bilbao. 1997, New York: Gerd Hatje Verlag.
Hopkinson, N., R.J.M. Hague, and P.M. Dickens, Rapid Manufacturing. An Industrial
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presented at the Rapid Tech 2008, Erfurt.
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benefits, tomorrow’s challenges. Paper presented at the tct live 2010, Birmingham.
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262
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Wohlers, T. (2007). Wohlers Report 2007, Rapid Prototyping and Manufacturing, State
of Industry, Annual Worldwide Progress Report. Fort Collins, Colorado, USA.
Wohlers, T. (2008). Wohlers Report 2008, Rapid Prototyping and Manufacturing, State
of Industry, Annual Worldwide Progress Report. Fort Collins, Colorado, USA.
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of Industry, Annual Worldwide Progress Report. Fort Collins, Colorado, USA.
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19/4, 18.
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263
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Weblinks
General information:
• Terry Wohlers is an insider in AM related to the industry and business markets:
http://www.wohlersassociates.com/
• Homepage of the Ennex Corp. about ‘fabbers’:
http://www.ennex.com/~fabbers/
• Castle Island’s Worldwide Guide to Rapid Prototyping:
http://www.additive3d.com/
• RT e-Journal: web-journal of the Technical University RWTH Aachen:
http://www.rtejournal.de/
• Z Punkt - the foresight company: German consultancy for future related questions:
http://www.z-punkt.de/
Manufacturer of AM systems:
• Objet: Company site about the PolyJet™ method:
http://de.objet.info/
• Optomec: Company site about the LENS and M3D methods:
http://www.optomec.com/site/index
• Concept Laser: Company site about the LaserCusing method:
http://www.concept-laser.de/
• 3D Systems: Company site about the SLA method and various DIY applications:
http://www.3dsystems.com
• Arcam: Company site about the EBM method:
http://www.arcam.com
• EOS: Company site about the SLS and DMLS methods:
http://www.eos.de/
• SLM Solutions: Company site about the SLM method:
http://www.slm-solutions.com/
• ContourCrafting, a technology to ‘print’ houses:
http://www.contourcrafting.org/
AM service providers:
• 1zu1 Prototypen: A service homepage for RP and AM
http://www.1zu1prototypen.com/index.htm
• FKM: A service homepage for RP and AM:
http://www.fkm-sintertechnik.de/index_de
• E-machine shop: A service homepage for RP and AM:
http://www.emachineshop.com/index.htm
• RTC: A service homepage for RP and AM:
http://www.rtc-germany.com/index.html
• 4D Concepts: A service homepage for RP and AM:
http://www.4dconcepts.de
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•
•
•
•
Fabtory: A service homepage for RP and AM:
http://www.fabtory.de/
Rapid Objects: A service homepage for RM:
http://rapidobject.com/
Freedom of Creation: A service provider for jewellery and design objects:
http://www.freedomofcreation.com
Materialise: A service homepage for RM:
http://www.materialise.com
Research and development / teaching:
• TNO NL, the Dutch pendant of Fraunhofer-Gesellschaft:
http://www.tno.nl/content.cfm?context=thema&content=prop_case&laag1=892
&laag2=906&laag3=83&item_id=1445
• Fabaroni, a homemade 3D printer, project of MIT:
http://fab.cba.mit.edu/classes/MIT/863.07/11.05/fabaroni/
• Centre for Bits and Atoms: Prototype laboratory at MIT:
http://cba.mit.edu/
• RepRap: Research project at University of Bath:
http://reprap.org/wiki/Main_Page
• RM Platform: European collaboration on Rapid Manufacturing:
http://www.rm-platform.com/
• Fraunhofer IFAM: Project pages on RP applications:
http://www.ifam.fhg.de/index.php?seite=/2801/rapid-product-development/
• Fraunhofer-Allianz Generative-Fertigung: Alliance of research institutions for AM:
http://www.rapidprototyping.fhg.de
• Loughborough University: Additive Manufacturing Research Group:
http://www.lboro.ac.uk/research/amrg/
• Loughborough University: 3D Concrete Printing: an innovative construction process:
http://www.buildfreeform.com/index.php
Trade fairs:
• Euromold, Frankfurt a.M., Germany, one of the most important trade shows for AM:
http://www.euromold.com
• RapidTech, Erfurt, Germany, trade show and conference on AM:
http://www.rapidtech.de
• Hannover Messe, an important trade show around innovation and manufacturing
technologies:
http://www.hannovermesse.de
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Glossary
Abbreviation /
Term
Description / Explanation
3DP
3D Printing; AM process
ABS
Acrylnitril-Butadien-Styrol-Copolymerisat; plastic compound
AM
Additive Manufacturing; general term for additive processes / layered production
ASTM
American Society for Testing and Materials
BIM
Building Integrated Modeling
Blob
Architectural design without orthogonal elements or joining (example: Kunsthaus Graz)
CAAD
Computer Aided Architectural Design
CAD
Computer Aided Design
CAD-CAM
Computer Aided Design-Computer Aided Manufacturing; transition from computer aided design and
­planning to computer aided realization of such designs
CAM
Computer Aided Manufacturing
CATIA
Computer Aided Three-Dimensional Interactive Application; software for 3D modeling of complex structures;
originated from aerospace applications
CC
Contour Crafting; AM process
CLAD
Construction laser additive directe; DMF-development from France; AM process
CNC
Computer Numeric Control
DGF
Direct Glass Fabrication; direct manufacturing of building components in glass (invented by Façade Research
Group, TU Delft)
DLP
Digital Light Processing; AM process
DM
Direct Manufacturing; general term for additive processes / layered production
DMDS
Directed Metal Deposition System; DMF-AM process
DMF
Direct Metal Fabrication; direct manufacturing of parts in metal
DMLS
Direct Metal Laser Sintering; DMF-AM process
DIY
Do-it-yourself
EBF³
Electron Beam Free Form Fabrication; DMF-AM process
EBM
Electron Beam Melting; DMF-AM process
FDM
Fused Deposit Modeling; AM process
FEA
Finite Element Analysis
FEM
Finite Elemente Methode (German) » Finite Element Analysis
FFF
Free Form Fabrication; general term for additive processes / layered production
FGM
Functionally Graded Materials; allows for merging of different materials and properties within one produced
part
GIS
Geographic Information System
IGES
Initial Graphics Exchange Specification; Industry file-standard for exchanging CAD files
LENS
Laser Engineered Net Shaping; DMF-AM process
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Liquid
Architecture
general term for digitally planned architectural designs, using the freedom of form from the applied CAD
software (see: M. Eekhout: Tubular Structures in Architecture; 2011)
LMD
Laser Metal Deposition; general term for DMF-AM processes
LS
Laser Sintering; AM process » SLS
M3D
Maskless Mesoscale Materials Composition; Aerosol Jetting System, AM process
MC
Mass Customization; individualized mass production; approach in product design: from ‘mass production’
and ‘individual customization’; paradoxon, but feasible with new technologies!
NURBS
Non-Uniform Rational B-Splines; multiple shaped line, defined from the computer for the representation of
3D-surfaces; originally invented the design of ship hulls, car bodies and aerospace exterior surfaces
ODM
On Demand Manufacturing
PF
Personal Fabber, Personal Fabricator » 3D-Desktop-Printer for the consumer market
PIM
Plastic Injection Molding; Injection-molding process for thermosets
RM
Rapid Manufacturing; evolutionary step from Rapid Prototyping (RP); describes the manufacturing of end use
parts with AM
RP
Rapid Prototyping; original application of AM technologies for the manufacturing of prototypes in product
development
SFF
Solid Freeform Fabrication; general term for additive processes / layered production
SLA
Stereolithography; AM process
SLA
Stereolithography Apparatus; if used for AM system
SLM
Selective Laser Melting; DMF-AM process
SLS
Selective Laser Sintering; AM process » LS
STL
Standard Triangulation Language; AM file-format, originates from „STereoLithography term“
Tissue Engineering
Technology that is used to generate tissue from human cells for the application in case of destroyed or harmed
tissue after accidents or body impact
VDI
Verein Deutscher Ingenieure; German Society for Standardization
Voxel
from Volumetric Pixel; merging of terms Pixel (definition of reference-point in digital image) and volume
definition of solids; aims toward the possibility of defining any point within 3D-modelled solids; would then
allow for defining material disposition within solids of 3D model
267
Additional information PhD thesis
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Index of figures and tables
I would like to thank all the image providers for their support of my work. They are
mentioned in this index. All other illustrations were created for this thesis by the author
or were provided by members of the Façade Research Group / TU Delft.
Especially some of the imagination-illustrations in § 4.2 were created in workshops
and seminars together with students, guests and members of the Façade Research
Group / TU Delft.
Every reasonable attempt has been made to identify owners of copyright or the source
from which they were taken especially in case of websites. If unintentional mistakes or
omissions occurred, I sincerely apologise and ask for a short notice. Such mistakes will
be corrected in the next edition of this thesis, or by time it will be officially published.
Figure
1 Mike Davies
12
Daan Rietbergen, FRG TU Delft
28
SLM Solutions GmbH, Lübeck, Germany
Bherokh Khosnevis, University of Southern California, USA
37, 88
Krista Polle, TNO Netherlands
41 - 43
Cousineau, L. and N. Miura
44, 45
Gramazio & Kohler Architekten, Zürich, Switzerland
45
Ralph Feiner, Switzerland
53, 55, 58, 60
Kawneer Alcoa, digital catalogue
65, 82
Klaus-Martin Hees, Kawneer Alcoa, Iserlohn, Germany
75
FKM Sintertechnik GmbH, Biedenkopf, Germany
90, 91
Marcel Bilow, FRG TU Delft
91
Leonie van Ginkel, TU Delft
83 Soumen Adhikary, India
84, 85
Ulrich Knaack, FRG TU Delft
86
NASA, JPL-Caltech
94, 95 Adrian Bowyer, University of Bath, England
107, 108 Terry Wohlers, Wohlers Associates, Fort Collins, USA
109, 110 Nathan Volkers, TU Delft
33-35, 87
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Index of figures
Figure 1
Concept sketch of the Polyvalent Wall by Mike
Davies. 18
Figure 2
Overview ‘Additive Fabrication’; use and
allocation of various terms for the different areas
of the AM industry 19
Figure 3
a) Screenshot of FDM job preparation on the
computer; software used is Catalyst: the 3D *stl.
file after the import.
b) The 3D *stl. file after the slicing was done by
the software.
c) In blue: the outline of the support structure; the
first layer on top of the building platform.
d) In blue: outlines and filling of the support
structure; in red: outline of the ABS part; in green:
filling of the ABS part. 22
Figure 4
Structure of the dissertation (schematic
representation of the work). 26
Figure 5
a.) CAD model; b.) slicing process; c.) building
process. 31
Figure 6
Schematic drawing of an FDM method
and surface steps depending on the model
contour. 32
Figure 7
Jewellery part designed for AM by FOC,
Amsterdam. 34
Figure 8
Lighting Design with AM by FOC, Amsterdam. 34
Figure 9
a) Tool with integrated cooling channels;
b) Illustration of contour conform cooling
channels. 34
Figure 10
Family tree ‘AM methods’. 37
Figure 11
Schematic drawing: SLA method 39
Figure 12
Lighting Design produced with SLA 39
Figure 13
Schematic drawing: LS method 40
Figure 14
Sample piece produced with LS 40
Figure 15
Schematic drawing: FDM method 41
269
Additional information PhD thesis
Figure 16
The visible structure of the different layers after
completion of the FDM print job. In white: the
ABS material; in brown: the soluble support
structure 41
Figure 17
Schematic drawing: 3DP method 43
Figure 18
3DP part with representative colour coding of a
FE-analysis 43
Figure 19
Schematic drawing: PolyJet™ method 44
Figure 20
PolyJet process during the UV-light curing of
the plastic material on the building platform
(below). 44
Figure 21
Not yet assembled RepRap kit; Hochschule OWL
2012 46
Figure 22
Self-assembled RepRap; FH Darmstadt 2010 46
Figure 23
Support structure (light grey) of a DMF part (dark
grey) after separation from substrate plate, @
FKM Sintertechnik GmbH 47
Figure 24
Inside view of DMF part: connective points of the
now removed support structure 47
Figure 25
DMLS support structures still attached to the part
and substrate plate. 48
Figure 26
DMF part of a turbine with internal honeycomb
structures, by ‘layerwise’ @ RapidPro2012,
Eindhoven 48
Figure 27
Parts produced with the CLAD system; surfaces
are still rough and need to be post-processed 51
Figure 28
System by SLM-Solutions, method: Selective Laser
Melting (SLM) SLM 280 HL; Imagery courtesy of
SLM-Solutions. 52
Figure 29
LaserCusing system with mounted substrate
plate, @FKM Sintertechnik GmbH 53
Figure 30
Substrate plate for LaserCusing process with
built upon DMF part on it, @FKM Sintertechnik
GmbH 53
i
Figure 31
DMF hip implant made from titanium; fixations
and a rough structure for the bone material to
grow inside are provided directly from the CAD
file. Customised part sizes are available. 54
Figure 32
DMF part in titanium; part height is ~ 20mm;
the rough surface is clearly visible and shows the
challenges for end use parts. 54
Figure 33
Size of a Contour Crafting wall in comparison
to a human being, Imagery courtesy of B.
Khoshnevis. 56
Figure 34
Contour Crafting ‘nozzle’ to generate concrete
parts with internal light-weight structures,
Imagery courtesy of B. Khoshnevis. 56
Figure 35
Visualisation of Contour Crafting set-up for the
production of housing. Imagery courtesy of B.
Khoshnevis. 57
Figure 36
Schematic presentation of the increased process
chamber dimensions since 2008. 74
Figure 37
Prototyp of FGM part produced with the High
Viscous Inkjetting system of TNO 78
Figure 38
Beta system for High Viscous Inkjetting of
TNO 78
Figure 39
a.) Homogenous material;, b.) joined material; c.)
Functionally Graded Material (FGM) 78
Figure 40
Smart material used in toddlers’ spoon to
indicate too hot served food by colour change at
the tip. 82
Figure 41
Robot system ‘T-Up-System’ by Taisei Corp. 85
Figure 42
Concrete robot by Takenake Corp. 85
Figure 43
Welding robot, Takenake Corp. 86
Figure 44
Test facility @ ETHZ: a.) the range of the robot arm
on the rails; b.) the tool to handle the brick; c.)
the application of the glue to the brick. Imagery
courtesy of Gramazio-Kohler, Switzerland. 87
Figure 45
a.) Digital idea for the wall element with ‘grapes
in a basket’; b.) project application: materialising
the idea with bricks into prefabricated wall
elements; c.) the final façade design. Imagery
courtesy of Gramazio-Kohler and Ralph Feiner,
Switzerland. 88
Figure 46
Façade development. 96
270
AM Envelope
Figure 47
Façade functions 98
Figure 48
Consistent AM design 100
Figure 49
Principle application of corner cleats for windowframe mounting. 102
Figure 50
Corner cleat gluing, @ Kolf en Molijn, façade
manufacturer, Netherlands 102
Figure 51
Corner cleat aluminium profiles; corner cleat
cutting with circular saw, @ Kolf en Molijn, façade
manufacturer, Netherlands 103
Figure 52
Storage boxes for the various types of corner
cleats, @ Kolf en Molijn, façade manufacturer,
Netherlands 103
Figure 53
Corner cleats for non-orthogonal window
frames; angle manually adjustable; Imagery
and illustrations from Kawneer-Alcoa digital
catalogue, Issue 10/2010 104
Figure 54
Rendering of 271.xx, detail; left: standard solution
digitally drawn from e-catalogue; right: AM
optimized solution; digitally reduced material and
light weight structures. Digital branding on the
side of the part: this could also be used for part
identification. 105
Figure 55
Drawing of standard corner cleat 272.xx from
Alcoa e-catalogue. 105
Figure 56
Original aluminium corner cleat and a first
prototype with integrated snap-on functions and
leightweight structures (right). 105
Figure 57
Rendering of part detail: 272.xx, AM optimized
solution; digitally reduced material and snap-on
features for additional fixation in the Aluminium
profiles; digitally drawn from e-catalogue. 106
Figure 58
To the left: standard corner cleats made from
aluminium profiles; to the right: AM corner
cleats made from ABS plastic with the FDM
technology. 107
Figure 59
To the left: standard corner cleats made from
aluminium profiles; to the right: AM corner
cleats made from ABS plastic with the FDM
technology. 108
Figure 60
T-connector for orthogonal connection in AA-100
mullion and transom façade system by Alcoa;
Imagery and illustrations from Kawneer-Alcoa
digital catalogue, Issue 10/2010. 108
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Figure 61
Standard T-connector mounted to AA-100 mockup. 109
Figure 62
To the left: standard free-form element, @ Kolf en
Molijn, façade manufacturer, Netherlands;
to the right: standard free-form connector,
@ Kolf en Molijn, façade manufacturer,
Netherlands. 110
Figure 63
3D connector: rendering (left), printed part in
stainless steel (right), realized on a DMLS system
by EOS @ FKM Sintertechnik GmbH 111
Figure 64
Digital T-connector mounted to AA-100 mockup. 111
Figure 65
FE-analysis results; conducted by Kawneer-Alcoa
during the project. 112
Figure 66
Evolution from Standard (left), to ABS Prototyp
(middle), to 3D connector in Stainless Steel
(right). 112
Figure 67
Non orthogonal façade construction, resulting in
a joining detail that is inadequately solved with
silicone. 114
Figure 68
Rendering, NEMATOX I, 3D façade node for Alcoa
‘Next’ façade system. 115
Figure 69
Principle of construction for façade node within a
façade system; all angles can be digitally adjusted
to the desired geometry and deformation. 116
Figure 70
Rendering: NEMATOX II, 3D façade node for Alcoa
‘AA-100’ façade system. 117
Figure 71
Nematox II mounted to AA-100 mock-up. 117
Figure 72
Nematox II mounted to AA-100 mock-up;
detailed view of the aluminium part. 118
Figure 73
Printed nodal point in aluminium, realized
on a ConceptLaser system by EOS @ FKM
Sintertechnik GmbH 118
Figure 74
Printed nodal point in aluminium, realized
on a ConceptLaser system by EOS @ FKM
Sintertechnik GmbH 119
Figure 75
Build job preparation: screenshot of orientation
of Nematox II within the DMLS building
chamber representation; indicated in red is the
needed support structure; @ FKM Sintertechnik
GmbH 120
Figure 76
Representation of file optimisation in several
cycles 128
271
Additional information PhD thesis
Figure 77
Representation of AM part optimisation in several
cycles 129
Figure 78
Representation of the optimisation aspects and
related areas 132
Figure 79
Evaluation schematic for AM envelope
principles. 141
Figure 80
Bilow, Ginkel: manual prototype ‘RSS’ 160
Figure 81
Left: rendering of the integrated sun shading
device; middle, right: Images of the AM prototype;
realized in different materials with the PolyJet
technology. 161
Figure 82
Mounting details for a standard window by
Alcoa ‘AA-720’. Imagery and illustrations
from Kawneer-Alcoa digital catalogue, Issue
10/2010. 163
Figure 83
Left: Erich Mendelsohn, Einstein Tower, Potsdam,
1920-24;
right: elevation after the restoration in 2000; b.)
detail of the entrance. 165
Figure 84
Left: view of Kunsthaus Graz in the middle of Graz,
Austria. A ‘Friendly Alien’ in a historical setting.
right: close-up of a ‘Nozzle’; cladding was done in
PMMA panes with point fixations.. 166
Figure 85
Left: view of Walt Disney Concert Hall, Los Angeles,
California;
right: Close-up of the primary structure that was
built in order to allow for the free form shape.
Cladding is done in metal plates,
fixed to substructure. 168
Figure 86
Left: Astronaut Buzz Aldrin, lunar module pilot,
walks on the surface of the Moon near the leg of
the Lunar Module (LM) “Eagle” during the Apollo
11 extravehicular activity (EVA). Astronaut Neil
A. Armstrong, commander, took this photograph
with a 70mm lunar surface camera.
Right: Astronaut Eugene A. Cernan, Apollo 17
mission commander, makes a short checkout of
the Lunar Roving Vehicle during the early part of
the first Apollo 17 extravehicular activity (EVA-1)
at the Taurus-Littrow landing site. This view of
the “stripped down” Rover is prior to loadup. This
photograph was taken by Geologist-Astronaut
Harrison H. Schmitt, Lunar Module pilot. The
mountain in the right background is the East end
of South Massif. Imagery courtesy by NASA. 203
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Figure 87
ContourCrafting: Printed model of a lunar cupola
structure (left); internal structures of cupola
with printer head (right). Imagery courtesy by B.
Khoshnevis. 204
Figure 88
Gradient spiral prototype with fading materials,
produced with High Viscous Inkjetting technology
by TNO. 215
Figure 89
Left: Beta system of a glass powder printer at TNO
in Eindhoven; the principle was adopted by Saint
Gobain Glass and is now commercially used for
façade projects.
Right: Application of the glass powder printer
for the ‘Beeld –en Geluid’, Hilversum; all glass
panes in the façade are individually coloured with
printed glass powder particles. 216
Figure 90
Schematic drawing DLP method 217
Figure 91
Casting modells for jewellery produced with
DLP 217
Figure 92
Schematic drawing LOM method 220
Figure 93
One available product for LOM by Solidimension;
using PVC film (bottom, right) for part
production. 220
Figure 94
RepRap, Darwin1; Developed at University of
Bath, England. 223
Figure 95
RepRap inventor Adrian Bowyer (left) with first
and second generation of RepRap 223
Figure 96
[email protected] (left); extrusion nozzle (right) with
medical syringe as the nozzle device. 225
Figure 97
Technical drawing of the standard T-connector
for a stick system; used as digital background for
optimisation. 229
Figure 98
Technical drawing of the standard T-connector
for a stick system; details and dimensions for
the optimisation process. All screw channels and
technical features were re-constructed in the
advanced connector. 230
Figure 99
The first adjustment was the implementation
of two different angles; this would allow for
deformation in the façade. 231
Figure 100
Optimised part as result of the optimisation for
AM; in this part material was digitally ‘cut off’,
where it is structurally not needed. 232
272
AM Envelope
Figure 101
Technical drawing with real dimensions of the
Nematox II; top view. 233
Figure 102
Technical drawing with real dimensions of the
Nematox II; front view. 234
Figure 103
Technical drawing with real dimensions of the
Nematox II; side view. 235
Figure 104
Technical drawing with real dimensions of the
Nematox II; isometric view. 236
Figure 105
Different phases of the ideation process. 241
Figure 106
Imagination workshop at UN Studio, Amsterdam,
May 2010. 244
Figure 107
AM market development and growth rates;
source: Wohlers Associates; report 2010. “The
previous chart gives estimated revenues (in
millions of dollars) for additive manufacturing
products and services worldwide. The lower
portion of the bars indicates products, while the
upper portion indocates services. The bars for
2010 and 2011 are forecasts.” 248
Figure 108
Expected Growth of Additive Manufacturing for
Part Production Applications; source: Wohlers
Associates; report 2009. 248
Figure 109
AM roadmap (revised by the author according to
Volkers, 2010) 249
Figure 110
Cost comparison: conventional technologies and
AM (Volkers, 2010). 251
Figure 111
Gartner Hype Cycle 2012, source: Gartner.
com. 252
Figure 112
Product sophistication: by Tillmann Klein. In:
‘Integrated Façade Components’ presentation,
Spring 2009, Delft University of Technology. 254
Figure 113
Faguswerk by Walter Gropius,1920. The first
curtain wall façade in Germany. 254
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Index of tables
Table 1
Overview of the described AM processes with
abbreviation, system denomination, size of the
building chamber and main material groups. 60
Table 2
Matrix I: potential of AM processes regarding
different aspects of manufacturing with AM, and
the AM processes themselves. 61
Table 3
Matrix II: further assessment of the potential of
AM on the background of Matrix I 63
Table 4
Explanation for the used quantification in Matrix I
and Matrix II 63
Table 5
The basic materials in plastics for AM, and the
suitable AM process to use them. 68
Table 6
The basic materials in metals for AM, and the
suitable AM process to use them. 70
Table 7
The basic other materials for AM, and the suitable
AM process to use them. 71
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A III Personal information
Curriculum Vitae
Dipl.-Ing. Holger Strauß
1974
Born in Wuppertal, Germany
1996 - 1999 Vocational training as cabinet maker / joiner
2001
Certified as log home builder, Canada
2001 - 2003Degrees from further education:
Master cabinet maker,
Certified engineer for the care and conservation of historical buildings – specialised in
wood constructions.
2003 - 2009
Freelance teacher: specialised in hands-on vocational training for journey men in carpentry.
2005 - 2008Studies of architecture at the University of Applied Sciences - Hochschule
Ostwestfalen-Lippe, Detmold, Germany.
Diploma in architecture
Since 2008Project leader ‘Research and Development’ at Hochschule Ostwestfalen-Lippe.
Freelance architect.
Member of the Façade Research Group at TU Delft. Guest researcher.
PhD candidate at TU Delft, Chair ‘Design of Construction’, Prof. Dr.-Ing. Ulrich Knaack
Since 2009Manager of the M.Eng. programme ‘International Façade Design and Construction
(IFDC)’ at Hochschule OWL, Detmold, Germany.
Contact: 275
[email protected]
Personal information
i
Acknowledgments
First and foremost I would like to thank Uli Knaack, who accompanied this work from
the beginning and helped to shape and fill it. Without his undeterred trust in the power
of innovation of this ‘freak’ topic, this work might not have reached the presented
scope and depth.
I would also like to express my gratitude to Klaus-Martin Hees at Kawneer-Alcoa, who,
as the person primarily responsible, supported and encouraged the research project
‘Influence of additive processes on the development of façade construction’.
And I would like to thank Holger Techen who critically observed this work and provided
me with valuable criticism.
In addition my thanks go to Usch Engelmann for the translation, to Till Klein for his
structured feedback and critical analysis, and to the members of the Façade Research
Group for interesting discussions amongst specialists.
To Andrea and Jarne, to my mom.
In great appreciation I dedicate this work to my father, Dipl.-Ing. Friedel Strauß, from
whom I have learned to structure and to organize, as well as many more things that I
was not aware of during his lifetime.
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AM Envelope
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